Science fiction has allowed for the investigation of some of the most wonderful advancements made by humankind, but the genre has also explored its most sinister ambitions. It has compelled us to search the stars in wonder looking for signs of life, as well as for signs of humanity’s impending doom. ’90s sci-fi attempted to predict the future of our species at the dawning of the New Millennium, and developments in technology also improved on ’80s sci-fi films, making ’90s sci-fi movies some of the biggest blockbusters of the decade.

The ’90s saw such colossal films as Jurassic Park in 1993 , Independence Day by 1996, and The Phantom Menace and The Matrix in 1999. This decade also saw the dwindling of sci-fi films featuring true “monsters”, as the sci-fi of the ‘oos became more streamlined and psychological. In an ode to some of the last great creature features, below you’ll find the scariest sci-fi monsters of the ’90s, ranked.

THE MARTIANS (Mars Attacks, 1996)

Partly because of his love for the sci-fi B-movies of the ‘50s and ‘60s, and partly because he’d never branched out into that genre before, Tim Burton made the satirical alien invasion film Mars Attacks. He based it off of popular films of the Golden Age of sci-fi, such as The Day the Earth Stood Still and Invasion of the Body Snatchers, complete with ray-guns and flying saucers.

The designs for his aliens were particularly freakish looking - green skull-like faces with enlarged carnal cavities beneath clear space helmets. These bug-eyed aliens may have been comical at times, but they could also be ruthless, responsible for strange canine-human experiments as well as some of the most creative kills in all of science fiction.

SPIDER SMITH (Lost In Space, 1998)

Based off of the popular ‘60s series of the same name, Lost in Space was the cinematic version that improved the framework of the series with better visuals, a better plot, and marginally better acting. What the intrepid family of interstellar explorers doesn’t realize as it leaves Earth is that a dangerous threat has smuggled aboard that looks indistinguishable from them.

Their mission to help the human race populate other parts of the galaxy gets derailed when the ship’s physician in charge of their vitals, Dr. Smith, hijacks the ship. Unfortunately for them and for him, he’s been bitten by an alien arachnid, and by the end of the film has transformed into a horrific abomination that has the potential to unleash thousands of the spiders on Earth.

EDGAR THE BUG (Men in Black, 1997)

Men in Black combined the best of the buddy cop trope with the science fiction spectacle, giving audiences a fresh franchise with action, comedy, and amazing visual effects. Agents K and J (Tommy Lee Jones and Will Smith) battle a host of extraterrestrial threats as interstellar border agents, but their nastiest nemesis is The Bug.

The Bug begins as a crash-landed alien outside of NYC, where a simple farmer who’s curiosity gets the better of him becomes its host. He successfully re-enters human society, but soon K and J discover his true identity. Vincent D’onofrio made a career comeback with his performance as the farmer who transforms into a truly disgusting hybrid.

SIL (Species, 1995)

When a group of research scientists send messages into outer space, they hope that the electronic parcels containing information about human life will prompt a response from extra-terrestrials. Imagine their elation when an alien responds, explaining how to create endless fuel. Ascertaining the alien is a friendly species, they agree to splice the alien DNA with a human host when the aliens send them a message containing their genetic information.

The product of that splicing is Sil, who looks perfectly normal until she begins ageing at an advanced degree and proving hostile. The scientists try to kill her but she escapes into Los Angeles, intent on mating and producing offspring to begin usurping the human race. When in her true form, covered in tentacles, she resembles something from Alien, which is appropriate considering H.R. Giger did the design work for her prototype.

THE MIMICS (Mimic, 1997)

One of Guillermo del Toro’s first big hits was Mimic, about some truly advanced bugs that learn to mimic their prey. When an infestation of deadly cockroaches affects New York City, it’s up to an evolutionary biologist to figure out a way to stop them before they wipe out all of the children. She decides to introduce bugs into the population designed to kill off the more deadly species.

These are no ordinary roaches, however, and they soon adapt to the foreign bugs, before undergoing a mutation that would make them very similar to humans. Guillermo del Toro’s creative directing style as well as unique creature design approach made what could have been a hokey B-movie something truly horrific.

THE T-REX (Jurassic Park, 1993)

Spielberg’s famous action adventure Jurassic Park was based off of the sci-fi thriller of the same name by author Michael Crichton, who put just enough real science into the film to make the ramifications of using amphibian DNA to resurrect dinosaurs truly frightening. When a wealthy businessman tries to make a theme park on the concept, all hell breaks loose when the dinosaurs break free.

The king of the dinosaurs was responsible for some of the scariest scenes in the film, including the famous scene in the rain with the night-vision goggles. The T-Rex has reigned supreme in the franchise ever since, and is one of the last sci-fi monsters to still be going strong alongside the xenomorph from Alien and the hunter from Predator.

GRABOID (Tremors, 1990)

Tremors is really a classic ‘80s monster movie that happened to be released in 1990, but it still counts! Starring the all-American hero Kevin Bacon and Fred Ward (who would go on to be in the Tremors sequel), they’re two repairmen just trying to leave their small town lives behind when suddenly things get a little interesting.

After a slew of peculiar deaths and sudden earthquakes shake up the sleepy town of Perfection, Nevada, Val and Earl and teaming up with a seismologist to study just what’s going on down in the dirt. They encounter giant worm creatures that have nested beneath the town, hoping to use the townsfolk as a feeding supply. After this, graboids popped up in Mexico, Canada, and Africa, and may have been implanted by aliens eons ago.

BIORAPTORS (Pitch Black, 2000)

The late ’90s were particularly great for science fiction films. Not only were The Matrix and Episode I: The Phantom Menace released, two big blockbusters that changed the game for the genre (if not for cinema in general), but they would be followed by a small budget film called Pitch Black reminded audiences that sometimes less was more when it came to movie monsters.

The film focused on a ship filled with colonists, a bounty hunter, and his dangerous mark. After it crash lands on a remote planet, the remaining survivors must work together to gather resources. As they selfishly turn on each other, they’re unaware they’re being hunted by one of the planet’s inhabitants, proving that human greed isn’t the only danger they’ll need to defend against.

THE BUG (Starship Troopers, 1997)

The Bug is the colloquial term for the giant arachnid-like creatures that Earth’s finest space military takes on in Starship Troopers, a satirical science fiction film from the ‘90s starring Casper Van Dien and Neil Patrick Harris. When the threat of giant bugs invading Earth becomes a reality, Johnny Rico and his friends enlist after high school graduation to protect their planet.

Little did they realize that the bugs would overpower them with superior numbers, strategy, and method of attack. With acid for blood, giant pinching claws and mandibles, they’re an adversary that just keeps coming, and coming. One bug may not seem like that big a problem, but they’re rarely alone.

THE HARVESTERS (Independence Day, 1996)

Rarely has an alien invasion movie galvanized a nation like Independence Day, starring Will Smith, Jeff Goldblum, and a variety of stars as the brave humans who face the onslaught of a hostile extraterrestrial race bent on destroying humanity. When our US military takes down one of their saucers, we finally get a look at one of the drone pilots in a secret research facility.

The creature is bipedal, with long, stringy arms and strangely triangular heads. The tentacles sprouting from their backs can be used for tactile purposes like integrating into their ships’ biomatrix or just strangling human scientists who get too close. Highly intelligent and commanding superior technology, we almost lost the fight against them.