Star Trek Aliens That *Could* Have Been Terrifying…

A Star Trek spoiler warning.

Spoiler Warning: There are spoilers ahead for the following Star Trek productions: The Original Series Season 1, The Next Generation, Deep Space Nine, First Contact, Enterprise, Discovery Seasons 1-2, Picard, Strange New Worlds, and Section 31.

It’s Spooktober, the scariest month of the year! And what better way to celebrate than to talk about… Star Trek? That can’t be right!

Star Trek has dipped its toes in the horror genre on a few occasions – including in recent years. But that’s not really what I want to talk about today (though I suppose we’ll touch on some horror-tinged episodes as we progress). Instead, I want to take a look at a few of the franchise’s aliens that could have been terrifying… if their respective storylines had been written that way. In short, these are aliens that have horror potential, but because Star Trek is what it is… they never really managed to scare me!

Captain Kirk and the Gorn captain in a 2013 TV commercial.
A horrifying monster.

As usual, I like to give a small caveat. Everything we’re going to talk about is the entirely subjective, not objective opinion of just one old Trekkie. If you hate all of my ideas, think I’ve totally misunderstood something, or I exclude a faction that seems blindingly obvious to you… that’s okay! There’s plenty of room in the Star Trek fan community for polite discussion and respectful differences of opinion, and I share this piece in that spirit.

Now, a bit more detail is necessary on this idea, methinks!

Star Trek can do horror – and it can do horror-themed stories exceptionally well. But Star Trek is not primarily a horror franchise, and we often explore aliens through the lenses of exploration, first contact, diplomacy, friendship, curiosity, or war. There are many stories involving contact with alien races – and alien “monsters,” to use some Halloween-adjacent lingo – but most of them treat aliens as potential new friends rather than terrifying, incomprehensible adversaries. And even in stories where an alien is villainous or powerful, Star Trek tends to go for either some kind of peaceful resolution or more of an action-heavy tone rather than all-out horror.

Cropped painting of the USS Enterprise.
The Enterprise.

But there are some aliens, introduced throughout the franchise’s fifty-nine-year existence, which could feel genuinely terrifying if they were dropped into a story that really went for a horror tone. A great example of this is the Gorn: The Original Series depicted the Gorn captain as an enemy for Kirk, sure, and Kirk even describes the Gorn as a “monster” in the episode. But Arena (the only episode prior to Enterprise where the Gorn appeared) was a piece about exploration and understanding – with a healthy dose of action thrown in, of course.

But Strange New Worlds took the Gorn in a whole new direction, ramping up their more monstrous qualities, and leaning into a style of storytelling not unlike that seen in the 1979 classic film Alien. This is the kind of thing I mean: if Strange New Worlds can do it for the Gorn… what other alien races could see their more horrifying qualities ramped up? And could some of these be interesting for a future episode or series?

With all of the preamble out of the way, let’s take a look at five alien races that I think could have been terrifying!

Alien #1:
The Klingons

Still frame from Star Trek: Strange New Worlds showing an aggressive Klingon.
A Klingon as seen in Strange New Worlds.

By the time Star Trek had updated the design of the Klingons and delved a bit deeper into their warrior culture, a decision had already been taken to make the Klingons friendly. But if you think about it… a race of incredibly strong, bloodthirsty warriors who are eager to die in battle could be genuinely terrifying with the right script.

However… when Discovery stepped back in time and set up its Klingon war arc in Season 1, we didn’t really get that. There were some tense moments and some neat action sequences, but part of me thinks that there have probably been too many storylines with Klingon heroes and protagonists for long-time Trekkies to take them seriously as a threat in the future.

Still frame from Star Trek: The Next Generation showing a Klingon with a bat'leth.
Wielding a bat’leth.

If The Next Generation hadn’t gone down that route, though… there’s a ton of potential here. Imagine an episode set on a derelict ship where a lone Klingon warrior is slowly hunting down a Starfleet away team. Or a story set aboard a station like DS9 where a handful of Starfleet personnel are desperately trying to protect civilians from an onslaught of warriors who aren’t afraid to die in battle. The Klingons’ single-minded dedication to war and combat makes them frightening, and their physical strength when compared to (most) humans makes them truly dangerous opponents.

Unlike some other aliens we’re going to talk about, I very strongly doubt we’d ever get a Klingon-themed horror episode! It would be difficult to pull off after seeing hundreds of episodes with the likes of Worf, B’Elanna, Martok, Gowron, and so on, and I suspect the fan community wouldn’t really be on board with the idea, either. But I stand by my pick: with the right script, filmed in the right way, this warrior race could be absolutely terrifying.

Alien #2:
The Sheliak

Still frame from Star Trek: The Next Generation showing the viewscreen and a Sheliak.
A Sheliak on the Enterprise-D viewscreen.

Strange New Worlds took the Gorn – an alien race which had only appeared a couple of times in Star Trek – and turned them into a major antagonist. So… why not do something similar with the non-humanoid Sheliak? The Sheliak appeared in just one episode – and kind of similarly to the Gorn in Arena, they weren’t the only part of that story! In fact, only one individual was seen on screen, and even then, only for a few moments.

However, the Sheliak have a really interesting and unusual design, especially by Star Trek standards, and for a one-off alien race that hasn’t been so much as mentioned in more than thirty-five years… they’re pretty memorable. To me, anyway!

Still frame from Star Trek: The Next Generation showing Picard, Troi, and a Sheliak.
Picard and Troi aboard a Sheliak vessel.

The Sheliak’s inhuman nature and incomprehensible language already make for an intimidating starting point, but their approach to other races – including humans – could really jump-start the fear factor. Viewing other races as inferior, and having no qualms whatsoever about wiping out whole settlements is a frightening idea – and if the Sheliak can back that up with technology, weapons, or perhaps some kind of weird alien goo, I think the stage is set for a genuinely frightening adversary.

Being somewhat of a blank slate, there’s a ton of room to expand on our knowledge of the Sheliak. They’re sentient life-forms, not “monsters,” but there’s still a ton of frightening potential in any intelligent non-human alien.

Alien #3:
The Founders/Changelings

Still frame from Star Trek: Deep Space Nine showing the Female Changeling.
The Female Changeling from Deep Space Nine.

A shape-shifting enemy that can – and already has – infiltrated Starfleet and the Federation? That seems like something with a lot of horror potential! Look at the classic horror picture The Thing as a great example of how something like this could work. An impostor living amongst a Starfleet crew, slowly picking them off, and the survivors losing their minds not knowing who to trust. A story like that is textbook horror.

Picard’s third season had a chance to do this, but the story there leaned more on the mystery and action side of things, rather than horror. There were some shocking moments, and the idea that anyone could, in theory, be a changeling did set up some tension for a time. But then the story went in a different direction towards the end, so that terrifying potential didn’t really amount to much, at least not in terms of horror.

Still frame from Star Trek: Picard showing two changelings.
Changelings in Picard.

One thing we’ve never really seen in DS9 or Picard is a Founder shape-shifting into some kind of truly monstrous and powerful form. If they can take the shape of birds, humanoids, or even a cloud of gas, there’s nothing stopping them from turning into a three-metre-tall eldritch horror with tentacles and needle-sharp teeth! Again, these abilities have been teased sometimes, but never really taken advantage of in a horror sense.

There are timeline questions, of course. A story set after the Dominion War, in a largely peaceful era, would struggle to justify including the Founders as a major antagonist like this. But, as in Picard, there could be a renegade faction or even an individual. In any case, Star Trek has done some cool things with shape-shifters – but really hasn’t even scratched the surface in terms of their horrifying possibilities!

Alien #4:
The Borg

Still frame from Star Trek: Enterprise showing several Borg.
Borg drones i Enterprise.

The Borg are scary. They’re “space zombies,” as I wrote once, and part of what makes them so frightening is that every ally lost to assimilation becomes another enemy to fight. The Borg also embody the idea of a “fate worse than death;” losing one’s mind, being turned against one’s friends and allies, and continuing to exist in a kind of limbo state. But think about it… have any Borg episodes really fallen into the “horror” genre?

For years, I’ve wondered whether Star Trek should try a “Borg Invasion” television series – a show in which the Borg make a real push to assimilate the Federation and the Alpha Quadrant. Such a show, were it to ever exist, would undoubtedly benefit from leaning into a horror tone – at least some of the time. Ramping up the fear factor by showing that no main characters are safe, that the Borg are this unstoppable “force of nature,” only interested in assimilation… I think it could be exceptional if done well.

Still frame from Star Trek: The Next Generation showing a Borg drone.
The first Borg ever seen on screen.

There have been some scary Borg moments over the years, and the faction’s aesthetic really leans into horror tropes. But since the introduction of the Borg Queen in First Contact, I kind of feel like the Borg lost part of what made them so special in the first place. If it were up to me, I’d create a retconned version of the Borg akin to their original appearances in Q Who and The Best of Both Worlds – interested in assimilation and technology, and completely unable to be reasoned with, talked down, or negotiated with. That, in my opinion, is a huge part of what made the Borg unique – and scary!

But even with a Queen, there’s still a lot more Star Trek could do to give us a Borg horror story – even if it was just a one-off episode, not a whole show. An episode with a tone like All Those Who Wander or Shuttle to Kenfori would work exceptionally well with the Borg as antagonists.

Alien #5:
The Terrans

Still frame from Star Trek: Section 31 showing young San and Georgiou.
Mirror Georgiou and San.

If you know me, you’ll know that the Mirror Universe (and its Terran inhabitants) has never been my favourite part of Star Trek… and that’s putting it mildly! But I won’t deny the horror potential in the setting, which is all about murder, violence, and torture. Imagine an unsuspecting officer being transported there, totally unaware of what was happening, and being hunted down by an entire galaxy full of violent sociopaths!

In past Star Trek stories, the rare moments where a character has actually met their Mirror counterpart have been played humorously, but if you think about it, the idea of discovering that you essentially have an “evil twin” is another horror trope that the Mirror Universe could lean into. Being kidnapped by a Terran because your Terran counterpart is someone high up in the Imperial military would be absolutely terrifying.

Still frame from Star Trek: Discovery Season 3 showing Mirror Burnham.
Mirror Burnham.

Again, decades’ worth of pretty low-quality Mirror Universe stories – episodes which, intentionally or not, came across as being funny rather than thought-provoking or scary – definitely count against this idea! But a good enough script should be able to see the Terrans and their Mirror Universe as the terrifying antagonists that they could have been!

Plus, it would be nice to get a Mirror Universe story with genuine stakes and a fear factor, instead of hammy over-acting and one-dimensional characters. Maybe the Terrans wouldn’t be my first choice to write a horror story around, but I definitely think the setting could lend itself to something frightening.

So that’s it!

Still frame from Star Trek: Strange New Worlds Season 3 showing "zombies" breaking into a room.
Zombies!

We’ve talked about a handful of Star Trek aliens that aren’t usually all that scary… but *could* have been!

I hope this was a bit of fun, and a little bit of a thought experiment. Star Trek is, as I said earlier, not a franchise that usually delves deeply into horror. That’s not to say it never happens, because it does, and it can work really well! But it’s just not a genre that the franchise’s writers typically like to play around in. At most, we’ll get a one-off horror-tinged story. But a feature film or season-long arc still seems a long way away.

I have a couple of other horror/Halloween ideas that I hope to get around to before the 31st, but I’ve been exceptionally busy over the past couple of weeks, so I’m not sure if I’ll manage to do everything in my writing pile. Might have to save one or two of those ideas for Halloween 2026! Still, I hope you’ll check back, because I daresay I’ll have more to say about Star Trek, sci-fi, horror, and the wide world of geeky entertainment before too long! See you… out there.


The Star Trek franchise can be streamed on Paramount+ in countries and territories where the platform is available, and most shows and films are also available on various on-demand platforms, as well as DVD/Blu-ray. The Star Trek franchise – including all properties, shows, and films discussed above – is the copyright of Skydance/Paramount. This article contains the thoughts and opinions of one person only and is not intended to cause any offence.

Star Trek’s Scariest Alien Monsters!

A spoiler warning graphic.

Spoiler Warning: There are spoilers ahead for the following Star Trek productions: The Original Series Season 1, The Voyage Home, The Next Generation Season 1, Deep Space Nine, Voyager, Picard Season 3, and Strange New Worlds Season 1.

It’s Spooktober – the spookiest month of the year! So I thought we could have a bit of fun and talk about some of the scariest aliens and villains that the Star Trek franchise has brought to screen.

Star Trek isn’t a franchise that’s well-known for being all that frightening. I don’t think that’s a controversial statement at all – in fact, I’d wager that most TV viewers would consider it pretty tame, especially when thinking about the horror genre and alien monsters! But that doesn’t mean Star Trek is never scary. There are some wonderfully atmospheric episodes and stories scattered throughout the franchise’s fifty-eight-year history that have some of those more frightening elements.

Still frame from Star Trek: Picard Season 3 (2023) showing a Borg cube.

Today, rather than talking about individual stories or episodes, what I’d like to do is pick out some of the franchise’s scariest aliens, monsters, and villains – and talk about why they work so well, why they’re so intimidating, and perhaps even just the potential they have to be frightening or scary in future stories.

My usual caveat applies: everything we’re going to talk about is the entirely subjective opinion of one person only. If I miss something you think is blindingly obvious or if I include a “scary” alien that you think isn’t frightening in the least… that’s okay! There’s plenty of room in the Star Trek fan community for disagreement and differences of opinion.

With that out of the way, let’s talk about some of Star Trek’s scariest aliens and villains!

Number 1:
Q and the Q Continuum

Still frame from Star Trek: Picard Season 2 (2022) showing Q.

The Q are on the list less for their out-and-out fear factor and more for their potential. I don’t think there have been many terrifying or bone-chilling Q appearances – though I will entertain the argument that Q’s penchant for randomness can have an unsettling or unnerving quality. Things like conjuring up aliens in Napoleonic uniforms or a post-atomic courtroom would be incredibly frightening in real life, even if they’re portrayed more as chaotic and wacky when we see them unfold on screen.

The Q Continuum’s real fear factor comes from their apparently unlimited power. No other alien race in Star Trek is as powerful as the Q, and they could quite literally wipe out humanity, the Federation, or even the entire galaxy with a wave of the hand. Although we always see Q as humanoid, their true form is a mystery, and their power seems to be without limit – and without a reliance on technology. No war against the Q seems possible, and if they ever chose to move against the Federation (which they could do for reasons beyond our comprehension, or to prevent some kind of conflict in the far future that we have no inkling of right now) they could be far more destructive than even the Borg.

Number 2:
The Gorn
(As they appear in Strange New Worlds)

Still frame from Star Trek: Strange New Worlds Season 1 (2022) showing a juvenile Gorn.

The Gorn are one of Star Trek’s oldest alien races, appearing in the first season of The Original Series. But after that initial appearance and a few scattered mentions through The Next Generation era, they didn’t show up on screen again until Enterprise. That depiction wasn’t great, in my view – it relied too heavily on CGI that didn’t look great at the time and hasn’t aged well. But the return of the Gorn in Strange New Worlds has been a triumph.

After several episodes built up the terror of Gorn raids on the Federation, it was the episode All Those Who Wander that really showed us what this new depiction of the Gorn can do. Strange New Worlds’ writers unleashed the Gorn in an episode that, more than any other in the franchise, leans into the horror genre. The Gorn are depicted almost like the Xenomorphs from the Alien film series, possessing strength and stealth abilities that left the away team cornered.

Number 3:
The Founders/Changelings

Still frame from Star Trek: Deep Space Nine showing a changeling in their gelatinous state.

Maybe this one is a little controversial, but after the way Changelings were depicted in Picard’s third season I think we have a pretty good case to include them as a frightening bunch! The idea that shape-shifters could infiltrate Starfleet and the Federation was addressed in a fantastic Deep Space Nine two-parter: Homefront and Paradise Lost. These episodes took more of a political thriller/drama approach to the topic, but the core idea is a deeply unsettling one.

With the Dominion playing a growing role in Deep Space Nine, the idea of Changeling infiltrators was scaled back and only used sparingly – probably because it’s not an easy story to write or pull off successfully. But Picard Season 3 brought the idea back in a creative way, showing how deadly Changelings could be and how a Changeling plot could be an existential threat to the Federation.

Number 4:
The M-113 Creature
(a.k.a. The Salt Vampire)

Still frame from Star Trek: The Original Series Season 1 (1966) showing the M-113 Creature.

The first ever alien to appear on The Original Series remains one of the franchise’s most frightening! The episode The Man Trap kick-started the Star Trek franchise back in 1966, and the Salt Vampire was the first alien that audiences saw Kirk and the crew wrangling with. As discussed above with the Changelings, the alien’s ability to change shape and blend in added to its fear factor – but moreover, its true appearance is pretty unsettling even today. There’s something to be said for those old rubber suits, eh?

The Salt Vampire is a sci-fi take on ancient legends and creatures from folklore, and that gives it a uniquely frightening feel. Preying on some of these old primordial fears lends the creature a genuinely intimidating vibe, and its grotesque appearance just adds to that. The Salt Vampire is, however, a tragic figure, as it appears to be the last of its kind; more akin to an animal acting out of instinct than a truly nefarious villain.

Number 5:
The Borg

Still frame from Star Trek: First Contact (1996) showing a Borg drone.

In my essay The Borg: Space Zombies, I go into a lot more detail on this topic, but the condensed version is this: the Borg fill a similar role to zombies in horror fiction, while also picking up on both Cold War-era fears of brainwashing and concerns about technology getting out of control. The idea of assimilation is incredibly clever, as it turns every ally the heroes lose into a new enemy to fight, making the Borg grow in strength at the exact same rate as Starfleet weakens.

The idea of being assimilated and losing one’s mind and identity is arguably a fate worse than death – and we’ve got several examples in Star Trek of ex-Borg wrangling with the consequences of what the Collective forced them to do. I would note that the Borg’s fear factor has declined over the years, particularly during the latter part of Voyager’s run. Seeing Starfleet triumph over the same adversary again and again – no matter how intimidating it may be on paper – does start to take the shine off things.

Number 6:
Armus

Still frame from Star Trek: The Next Generation Season 1 showing Armus.

Armus has the distinction of being the first alien monster to kill a main character on a Star Trek TV series. There were many ways The Next Generation’s writers could have written out Tasha Yar when Denise Crosby opted to quit the show, but killing her off was a bold move. And doing so in such a brutal way, with Armus not even batting an eye at her death… it was quite something to see.

If you have the DVD or Blu-ray of The Next Generation it’s worth watching the actors and producers talk about working on the episode Skin of Evil, because creating Armus and performing around the inky-black oil slick was incredibly difficult for everyone involved to say the least! Jonathan Frakes in particular had a very tough time with Riker’s scene when he was pulled under the surface. Armus is a scary-looking villain, and also one that had a profound, long-lasting impact on The Next Generation.

Number 7:
The “Whale Probe”

Still frame from Star Trek IV: The Voyage Home (1986) showing the Whale Probe.

Although the tone of The Voyage Home is pretty light-hearted and comedic, the so-called “whale probe” that kicks off the plot is an incredibly terrifying adversary, when you think about it. The probe disables Starfleet vessels with incredible ease, and is resistant to weapons and all attempts at communication. The people of Earth have no idea what it wants, what its purpose is, or how to reason with it.

This monolith simply arrives unannounced, doesn’t declare its intentions, and seems to wreak havoc on Earth and Starfleet. That’s a pretty scary concept, in my view, as it could’ve gone pretty badly for everyone involved if Kirk and the crew hadn’t intervened!

Number 8:
The Pah-Wraiths

Still frame from Star Trek: Deep Space Nine Season 6 showing Jake Sisko possessed by a Pah-Wraith.

As with Armus, there’s something distinctly “evil” about the non-corporeal Pah-Wraiths. The way they’re presented in multiple Deep Space Nine episodes, where they’re deeply entwined with Bajoran religion, makes them out to be akin to demons or dark spirits – and we even see them “possess” several different characters. Their banishment to Bajor’s fire caves also ties into this demonic analogy.

In later seasons, Gul Dukat gets involved with the Pah-Wraiths, leading a cult on Empok Nor that’s genuinely unsettling in its depiction. The Pah-Wraiths have magical books, the power to turn people blind, and the desire to conquer the Prophets’ domain in the Wormhole; a truly frightening group!

Number 9:
The Conspiracy Parasite-Aliens

Still frame from Star Trek: The Next Generation Season 1 showing a parasite-alien.

The end of The Next Generation’s first season introduced a race of parasitic aliens that infiltrated Starfleet. Allegedly, the parasite-aliens were supposed to be connected to the Borg in some way, but this angle was later dropped. Still, they’re more than frightening enough on their own terms, and the idea that Picard and the crew wouldn’t be able to tell who was infected and who to trust made for an entertaining story.

Here in the UK, one scene toward the end of Conspiracy was cut from the original broadcast because of how gruesome it was! You know the one: where the “mother” parasite is killed and violently explodes. There’s something just unsettling about earwig-like alien parasites… just like the Ceti Alpha eel from The Wrath of Khan. Star Trek hasn’t revisited the parasite idea for a long time – maybe it could make for a fun and horrifying future episode?

Number 10:
The Krenim

Still frame from Star Trek: Voyager Season 4 showing Annorax.

The Krenim appeared in the Voyager two-parter Year of Hell, using their time-manipulation technology as a weapon. Repeated Krenim attacks against the USS Voyager left the ship in ruins, running on fumes, and many members of the crew dead or maimed. The captain of the Krenim time-ship, Annorax, was Khan-like in his single-minded obsession with restoring the Krenim colony that housed his wife and family, making him a frightening adversary.

Year of Hell is a pretty shocking episode, particularly in its second half. Seeing Voyager badly damaged, with whole parts of the ship uninhabitable, really hammers home how dangerous the Krenim and Annorax are as villains, and for a time their technology really does seem to be more than a match for Janeway and the crew.

So that’s it!

Still frame from Star Trek: The Original Series (1966) showing a Gorn.

We’ve picked out what I consider to be a selection of Star Trek’s most frightening aliens, monsters, and villains to celebrate the spooky season.

There are plenty of others that we could’ve included – either for their fully-blown fear factor or for their potential to do serious harm to our Starfleet heroes. And there are quite a few Star Trek episodes – a surprising number, really – that either lean fully into the horror genre or that have jump-scares or other frightening or unsettling moments. Last year, I put together a list of a few of them, which you can check out by clicking or tapping here if you’re interested!

So I hope this has been a bit of fun! I hope you’re having a fun and spooky October – and stay tuned, because I have a couple of other Halloween-themed ideas that may (or may not, time depending) make their way onto the website before the 31st. Don’t have nightmares!


Most of the films and episodes discussed above are available to stream on Paramount+ in countries and territories where the platform is available. They’re also available for purchase on DVD, Blu-ray, and video-on-demand. The Star Trek franchise – including all films, episodes, and other properties discussed above – is the copyright of Paramount Global. This article contains the thoughts and opinions of one person only and is not intended to cause any offence.