Just because a movie is not categorized as a horror movie does not mean that the filmmakers won't try to freak out their audience for a time or two. Sometimes even the most inconspicuous movies are just waiting to unleash some nightmare fuel in the form of some frightening creature.

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No genre is safe from these surprise monsters either, from high fantasy to sci-fi epics to regular old dramas and even children's movies. Sometimes the biggest scare is the one that comes out of nowhere, as is proved by these monsters who came to add a little bit of horror to their films.

The Dumpster Monster — Mulholland Drive

Hobo in Mulholland Drive

Mulholland Drive, like most of David Lynch's work, rarely ever gives viewers any real clues as to what is going on, preferring to leave things open to interpretation. There are several unsettling scenes in the movie, but by far the most horrifying come during a discussion between two men in a diner.

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The men, who have almost nothing to do with the movie outside of this scene, sit and talk like one of them begins describing a horrible feeling he has had recently. He blames it on a creature behind the restaurant, which he describes in great detail. The men go check to ease his mind, when they are suddenly greeted by the exact monster in one of cinema's greatest jump scares ever. It's an image that won't soon leave the viewer's mind.

The Demon Dogs — Ghostbusters

Ghostbusters is a beloved comedy with a hilarious script and great characters. It never really takes itself too seriously, although some of its soon-to-be-busted ghosts can be quite frightening. Even more than the librarian ghost or the zombie cab driver, the true forms of the Gatekeeper and Keymaster elicit some scares.

Though not quite as intimidating when possessing Rick Moranis or Sigourney Weaver, the ghosts soon revert to their original form of creepy, dog/lizard hybrids. The scene where they abduct Sigourney Weaver's character is also straight out of a horror movie, proving that even a comedy can fit in a few decent frights.

Rasputin — Anastasia

Rasputin villain song In the Dark of the Night

Grigori Rasputin was already a man not suited for a role in a children's movie, but 1997's underrated Anastasia somehow made him even creepier. Not content with having him be the crooked mystic he was in real life, the film turns Rasputin into a literal zombified sorcerer.

The Rasputin of the film has sold his soul for his powers, meaning that he is essentially the reanimated corpse of his former self. Add in his army of ghosts, his penchant for falling apart and reassembling, and a death sequence where he melts on-screen, Rasputin is pure nightmare fuel. And this movie is rated G.

Ceti Eels — Star Trek: The Wrath Of Khan

Wrath of Khan Ceti Eel

The Star Trek franchise has seen its fair share of intimidating beasts over its decades-spanning run, but none come close to the mind-controlling Ceti Eels in The Wrath Of Khan. Sicced early on by Khan on some of the Enterprise crew, the bug-looking creatures unsettled generations of fans.

Playing not only on the disturbing thought of an insect worming its way into someone's head but also the existential fear of losing control of one's own body, the eels bring horror both in how they look and what they do. The eels were unlike anything that had been seen in Star Trek before, and thankfully after.

Rancor — Star Wars Episode VI: Return Of The Jedi

A Rancor devouring prey in Star Wars

The other fan-favorite sci-fi juggernaut, Star Wars also has its fair share of creepy creatures in its extensive universe, but the rancor has to take the crown. While the rancor may have lost some of its mystique since its first appearance in Return of the Jedi, that introduction is still one for the ages.

A hulking behemoth living in the underbelly of Jabba the Hutt's palace, the rancor sets its sights on Luke Skywalker. Grotesque in appearance and capable of eating a person or alien whole, the rancor is a surprisingly frightening foe in a relatively family-friendly series. It is a far cry from the Ewoks at the end of the film.

Spinosaurus — Jurassic Park 3

Spinosaurus Jurassic Park 3

How does a series that featured a Tyrannosaurus rex in its first movie outdo that terror for its third? By throwing in the biggest land predator to ever exist, the Spinosaurus. The Spinosaurus quickly asserts itself as the biggest threat on the island by straight-up murdering the aforementioned T-rex singlehandedly.

While there is debate as to whether a real Spinosaurus could beat a T-rex or not, the movie version is quite an imposing threat. Bigger, faster, and more aggressive than the T-rex, the Spinosaurus is one of the franchise's deadliest Dinos. It was also semi-aquatic, meaning that the protagonists weren't even safe from it as they sail away from the island.

Cyborg Vera — Superman 3

Superman 3 Vera

The Christopher Reeve Superman movies are fondly remembered as a classic, campy movies that were fun for the whole family. The less fondly remembered Superman 3 however features one scene that terrified many children watching it for the first time.

Vera is a regular person who serves as a secondary villain throughout the movie, but when she is caught in the Ultimate Computer, Vera is turned into a cyborg in a disturbingly dark sequence. She screams as metal is grafted onto her before striking down her brother and main antagonist Ross. She and the audience were likely relieved when she was returned to her former self.

Shelob — Lord of the Rings: The Return of the King

Shelob wraps Frodo up

Arachnophobia is a common and arguably justifiable fear shared by many. Many films have used that fear against audiences, but few quite so well as Lord of the Rings with Shelob. Brought to life through incredible CGI and sound design, the giant spider queen manages to be even creepier than your garden variety giant spider.

Very quickly poisoning Frodo after slinking down from the shadows, Shelob webs him up and takes him back to her lair to eat. When Samwise Gamgee mounts a rescue mission, he and the audience are brought up close and personal with Shelob. If anyone needed any more proof that Sam is the best Hobbit, facing down Shelob more than clinches it.

The Pale Man — Pan's Labyrinth

The Pale Man using his hands to see in Pan's Labyrinth.

Guillermo del Toro is known for bringing fantastical and unsettling monsters to the screen, but the Pale Man from Pan's Labyrinth may still be his most iconic creation. A grotesque creature with no eyes, the Pale Man needed only one scene to ingrain himself into viewers' brains.

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The Pale Man's diet consists mainly of children, which is made clear when protagonist Ofelia must venture into his lair. Accidentally making him up, the Pale Man places two eyes on his palms and lurches towards Ofelia. In a movie with many monsters, both human and otherwise, the Pale Man is by far the king of them all.

The Mutant Bear — Annihilation

The mutant bear looks straight at the camera in Annihilation.

Depending on who you ask, Annihilation probably should be considered a horror movie. It is full of existential horror and disturbing imagery, but none anywhere near as haunting as the mutant bear. Early on, one of the members of the team is killed by a bear. Later on, when the team hears her cries for help, they believe she is alive.

After tying up her comrades, one of the team runs out and into the scariest movie monster of the decade. The bear's face is a decayed amalgamation of a human and animal skull, and its roar has been replaced by the distorted scream of the dead scientist. The fear of the scene is off the charts as the bear seemingly toys with its helpless victims. The mutant bear is not only the scariest non-horror monster, it is one of the scariest movie monsters ever.

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