The science-fiction genre has been responsible for some of the most iconic movie villains of all time. The likes of Darth Vader, the Xenomorph, and HAL 9000 all come from the world of science fiction. The bad guys in these worlds can often seem other-worldly, which adds to their terrifying nature.

The 2000s saw a number of influential and impactful sci-fi films being released, which meant some new sci-fi villains being introduced. Some of these villains were grotesque monsters, while others were humans who showed the most unsettling aspects of humanity. Here are the scariest 2000s sci-fi villains, ranked.

The Operative (Serenity)

After the cancellation of Firefly after a single season, many fans assumed that was the last they would see of Joss Whedon’s space adventure story. Remarkably, Whedon got the chance to continue his story on the big screen with Serenity. The original cast of the show returned to reprise their characters, and there was one notable new addition with Chiwetel Ejiofor’s The Operative.

The Operative is an agent working for the authoritarian organization known as the Alliance. The Operative quickly proves to be a formidable enemy with exceptional fighting skills. However, he is terrifying because of his professionalism as a killer, not stopping until the job is done.

Aliens (Signs)

Signs is sometimes looked at as the film that signaled M. Night Shyamalan’s decline as an exciting filmmaker. But despite some glaring issues with the film, there are still some great moments of suspense as the mystery of the alien invasion unravels.

The final moments of the movie make the aliens a little less effective as villains, but there are some truly scary moments with them throughout the movie. The sight of the alien standing on the farm roof or the infamous scene of the birthday news footage show that Shyamalan knows how to get a good scare.

High Chancellor Sutler (V For Vendetta)

The dystopian stories have always been a big part of the sci-fi genre, and V for Vendetta was another fun addition to the group. The movie takes place in a not-too-distant future where England has come under the authoritarian rule of High Chancellor Sutler (John Hurt) in the wake of turmoil throughout the world.

Sutler is scary as a villain because the concept of his character doesn’t seem farfetched. We have seen the kind of world leaders who use fear and uncertainty that is manufactured by themselves as a means to rise to power and silence anyone who dares challenge them.

Grant (Slither)

Before James Gunn was one of the biggest names in the comic book movie genre, he was still making lower-budget and grotesque horror films. Slither is his homage to B-movies and is set in a small town that becomes terrorized by disgusting slug-like creatures.

Michael Rooker plays Grant, the first victim on the slugs who becomes taken over by the creatures and gradually transformed into a huge and disgusting creature himself. The sight of Grant in his full monster-mode is truly revolting and makes for an unforgettable sci-fi creature.

Gwoemul (The Host)

Bong Joon-ho is receiving huge acclaim for his latest film Parasite, which is being called one of the best of the year. However, he has been making great movies for years, including this sci-fi monster masterpiece. The movie follows a South Korean family who desperately searches for their daughter, who was taken by a massive monster.

The creature’s design of the monster is unique and interesting, but it is the way Joon-ho shoots the monster sequences that are so effective. The first attack is seen from the perspective of one character and is does give a sense of what it might be like if a giant creature really did attack.

Pinbacker (Sunshine)

Sunshine is a thought-provoking and beautiful science-fiction thriller which follows a group of astronauts on a mission to restart the sun and save the Earth. The crew faces various challenges on their mission, but it is a human factor that turns out to be the real threat.

After encountering a shuttle from the previous failed mission, the crew’s ship is infiltrated by that team’s leader, Pinback (Mark Strong). The journey to the sun seems to have warped his mind, and Pinbacker now found a distorted religious view that makes him very dangerous.

Dren (Splice)

Splice is one of the smaller films on this list, but one worth seeking out. The film stars Adrien Brody and Sarah Polley as scientists who successfully splice human DNA with animal DNA to create a new being. They name the creature Dren and begin to raise it as it shows incredibly fast growth.

As Dren begins to mature faster and faster, she becomes more violent and begins changing in unexpected ways. The design of Dren is very unsettling as she looks almost human at times, but there remains something animalistic about her, which begins to show through her disturbing behavior.

Stargher (The Cell)

The Cell is an inventive serial killer thriller with an interesting sci-fi twist. Jennifer Lopez stars as a social worker who uses experimental technology to enter the mind of a killer (Vincent D’Onofrio) to save his intended victim.

The killer, Carl Stragher, has a tortured mind and genuinely thinks he is doing the right thing by killing people. However, as we venture deeper inside his disturbed mind, his darker thoughts come forward with terrifying results. The ways in which Stragher views himself in his mind are brought to life as horrifying beings.

Clover (Cloverfield)

We’ve seen a lot of found-footage movies in the horror genre, but it’s rare we get to see that formula play out in a big sci-fi movie. Cloverfield took just that approach to show a ground-level view of a giant monster attacking New York City.

The monster itself, named Clover by the filmmakers, is only seen in brief glimpses throughout the film as the protagonists run around the city trying to stay alive. However, this proves to be an effective technique as the unknown aspect of the monster makes it even scarier.

Mrs. Carmody (The Mist)

The Mist is another great Stephen King adaption about a group of people in a small town that becomes overrun by a mysterious mist. Soon it is discovered that deadly otherworldly creatures are hiding in the mist and a group of people take refuge inside a supermarket.

In a movie filled with terrifying monsters, the most unsettling villain in Mrs. Carmody (Marcia Gay Harden). She is a local unpleasant church lady who is always talking about the biblical end of times. While her ramblings are frustratingly ignorant, she manages to convince many of the people with unsettling ease and leads them to horrific acts to satisfy her warped religious views.