There have been countless alien movies, from horror to science fiction, and some of these had some of the ugliest aliens imaginable.

Prey arrived on Hulu and brought the Predator back to the world with a prequel story. While this took place in the 1700s, the Predator was as dangerous and advanced as ever, as it hunted humans for sport once again. Something else that never changed about this murderous monster is that, when the helmet comes off, it is one of the ugliest aliens in movie history.

Three are plenty of ugly aliens coming from the outer reaches of space, and typically the uglier and more horrific they look, the scarier they are. However, there are other aliens that might not be that frightening but are still ugly enough to make a person think twice before facing them one on one.

In 1988, John Carpenter directed one of the most beloved cult classics in science fiction movie history. They Live starred professional wrestling icon Rowdy Roddy Piper, and the plot revealed that aliens had already invaded Earth and had assimilated themselves by impersonating humans.

The only way to see the real identity of the aliens among the humans was by wearing special sunglasses. When Nada got the glasses and saw them, he recoiled in horror. With giant bulging red eyes and a blueish face, Nada gave them the nickname, "formaldehyde-face."

The 2009 sci-fi movie District 9 was an interesting take on alien stories, as the Prawns that lived on Earth were here as refugees. They arrived when their spacecraft showed up in 1982 and had over a million malnourished aliens onboard.

Earth agreed to help them, but their hideous appearances meant that most humans wouldn't accept them, forcing them to live in what amounted to an internment camp called District 9. The hatred toward the Prawns based on their looks was a huge part of the social commentary that director Neill Blomkamp set out to explore in his movie.

Not all ugly aliens in movies are horror creatures, and some aren't even bad guys. The Prawns in District 9 were not evil, but people still discriminated against them based on their appearance. Things were just as bad in E.T. when a scientist alien ended up stranded on Earth and scientists wanted to capture and experiment on him.

E.T. was in no way a bad alien, but he was a terribly ugly one. He was scary, with a long neck, giant probing eyes, a pug nose, and his insides even glowed. When he turned white and fossilized, it was the thing of nightmares. It is no wonder Gertie screamed in horror when she saw him.

There have been lots of aliens in the Marvel movies over the years. Thanos is giant and purple, Ebony Maw is abnormally pale and slender. Guardians of the Galaxy had aliens of all shapes and sizes, many frightening in appearance. But few of the aliens are as ugly as Venom.

Venom is scary in every conceivable way. He is giant, towering over people and casting an intimidating presence. However, his face tells it all, with crooked evil-looking eyes, a mouth full of razor-sharp teeth, and a long red tongue that would make Gene Simmons envious.

In Stephen King's It, the monster that killed children was an alien, as shown by his origin in the two-part movie by director Andrés Muschietti. Played in those movies by Bill Skarsgård, Pennywise the Dancing Clown was more terrifying than the classic Tim Curry version.

However, things got worse as the second movie moved on. He turned into the creature of nightmares when the adults in the Loser's Club went searching for him, and when they finally beat him, he transformed into a terrifying baby creature that gave viewers nightmares.

The first Men in Black movie brought fans a lot of different aliens. Some were fun, like the little insect creatures in the break room. Others were disturbing, like the talking pug. However, one was terrifyingly ugly and disturbing at the same time - the Bug.

The Bug was Vincent D'Onofrio's villain in the movie. He didn't know how to act or talk like a human, so all his moves were awkward and wrong. However, he also had no idea what to do with his face, causing it to droop and distort, making him unsettling in the most grotesque ways.

Before James Gunn joined the Marvel Cinematic Universe, he was making interesting smaller movies, and one of his best was the horror flick Slither. The movie starred Nathan Fillion as a small-town sheriff who realized that his town was infected by an alien parasite that threatened to consume everyone there.

The movie owes a lot to Invasion of the Body Snatchers, but it took the idea of aliens taking over bodies to a grotesque level. Michael Rooker starred as a man infected by the parasite, and by the end, he was a huge, mutilated mass of humanity with things growing out of him and dripping off him. It was horrific even after he exploded.

In 1979, Ridley Scott showed how terrifying science fiction horror could be when he released the movie Alien. The movie took place in the future and saw space travel as a normal occurrence. When a commercial space tug came across an abandoned ship, they investigated and found a house of horrors.

Aboard the ship was an alien known as a Xenomorph, and it proceeded to kill all the members of that ship's crew but one. This was an extremely ugly alien, designed by H.R. Giger, with an elongated cranium and a secondary jaw that shows sharp teeth and a hint of acid drool.

Prey reintroduced the world to the Predators, and it did it in a way that was better than almost every other iteration since the original movie. These are high-tech intelligent aliens who love to hunt humans and other species for sport. However, when the masks come off, their hideous appearance is often shocking.

The Yautja from the Predator movies has distorted-looking mouths, with teeth sticking out everywhere and sunken yellow eyes. The original movie even made a joke about it when Arnold Schwarzenneger's Dutch commented that the alien was "one ugly motherf***er."

The ugliest alien in movies came in the John Carpenter horror remake, The Thing. The movie takes place at a research laboratory in Antarctica where an alien parasite gets into the base and begins to wreak havoc. This creature can mimic anyone's looks, so the members of the base don't know if any of them are who they claim to be

However, the alien's biggest weakness is fire, and once hero MacReady figures out where he is, he sees what the creature really looks like, and it is the thing of nightmares. Rob Bottin worked on the creature effects and created an ugly alien that might be the most disgusting being ever seen in a movie.

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Shawn S. Lealos is a senior writer on ScreenRant who fell in love with movies in 1989 after going to the theater to see Tim Burton's Batman as his first big screen experience. Shawn received his Bachelor's degree in Journalism from the University of Oklahoma with a minor in Film Studies. He has worked as a journalist for over 25 years, first in the world of print journalism before moving to online media as the world changed. Shawn is a former member of the Society of Professional Journalists and current member of the Oklahoma Film Critics Circle. He has work published in newspapers such as Daily Oklahoman and Oklahoma Gazette and magazines such as Vox Magazine, Loud Magazine, and Inside Sports Magazine. His work on the Internet has been featured on websites like The Huffington Post, Yahoo Movies, Chud, Renegade Cinema, 411mania, and Sporting News. Shawn is also a published author, with a non-fiction book about the Stephen King Dollar Baby Filmmakers and has begun work on a new fiction series as well. Visit Shawn Lealos' website to learn more about his novel writing and follow him on Twitter at sslealos.