Anyone who saw King Kong or Godzilla walking down the street would not have to stop and wonder why the monster inspired such terror. (They'd be too busy running away!) A lot of horror movies have exploited the natural fear of creatures that are much larger than human size, the sort of beasts that might stomp on someone without slowing down -- or even realizing what they'd done.  

Other great horror movies have tapped into other fears. We recoil at the idea of being eaten alive, for example, but what if the creature's intentions are not quite so obvious? We've gathered a variety of monsters of different sizes to further explore why they're so terrifying.

The Host (2007)

As this clip vividly illustrates, there's nothing like a big hungry monster with a taste for people to strike fear into the heart of everyone. It's not just the creature's size, however, which is large but not overwhelming; it's also its speed and unpredictability that fan the fear-o-meter.

Pan's Labyrinth (2006)

In a magical labyrinth beneath her home, young Ofelia (Ivana Baquero) must complete a series of tasks to attain immortality. But she ignores a warning not to eat anything, thus awakening the Pale Man, whose terrifying qualities quickly becomes apparent when he decides to eat something, too.

The Descent (2005)

In Neil Marshall's unnerving thriller, a group of women cave explorers find themselves in a bad situation: lost in a cavern that's never been explored before. Bad turns to worse, however, when they realize they are not alone, but instead at the mercy of killer subterranean creatures who are far more suited than the women are to survive. The dark shadows and menacing sounds increase the fear factor.

The Blob (1988)

No one believes Meg (Shawnee Smith) when she tells of a horrible creature that devoured her friend. But they will believe soon enough after the frightening Blob makes its presence known and starts consuming more local citizens. Can anything stop the Blob?

The Fly (1986)

The brilliant scientist Seth Brundle (Jeff Goldblum) makes one fatal mistake in an experiment and soon finds himself becoming a terrifying monster.

The Thing (1982)

Kurt Russell and his fellow scientists at an Antarctic station have no idea what, exactly, the alien creature attacking them actually is. But what they quickly learn is that the creature's scariest weapon is its shape-shifting abilities.