Bats are creepy for many people. They often seem like rats with wings to us, they can spread rabies, and reside in all sorts of dark, foreboding places (caves, bell towers, abandoned houses, castles, crypts, etc) where humans themselves rarely venture. Out of over a thousand species, three are infamous for drinking blood, and have led to a strong association between bats and vampires despite a continental divide. As such, bats frequently show up as antagonists in horror themed media. They can be roughly divided into a few types that occasionally overlap:

1. Normal bats: Frequently depicted as The Swarm; a shrieking mass of menacing wings, regardless of whether or not they pose any actual danger to the cast. May be controlled or conjured by someone to form a Barrage of Bats.
2. Dire bats: Larger and more vicious than normal bats, and menacing even without The Swarm to back them up. These may be given a variety of overtly monstrous features and abilities, such as exaggeratedly large facial features, a vampiric thirst for blood, screeches and echolocation as strong as sonic weapons, or a complete absence of eyes.
3. Bat People: Monstrous, anthropomorphic creatures with a mixture of bat and human features.
4. Robo bats: Robotic bats.

If vampires can transform, their only or primary alternative form is that of a bat. Bat wings are also a frequent model for winged creatures of an Evil alignment. In video games, bats are among the most common enemy types in Underground Levels, where they appear as everything from small, darting annoyances to monstrous high-level enemies, and are also fairly common in Big Boo's Haunt.

In Real Life bats aren't actually all that bad, and probably among the most unfairly maligned animals. Most bat species only feed on insects, fruit, or nectar, and many species are very useful to mankind as pest-eaters, pollinators, and so on. The "shrieking" is often closer to benign chirping/clicking. Sometimes, they're even Ridiculously Cute Critters. In spite of being the largest bats, due to What Measure Is a Non-Cute? and Herbivores Are Friendly, fruit bats and flying foxes are rarely played for horror and more likely to be portrayed positively in fiction compared to their "uglier" yet much smaller microbat cousins.

The part about them spreading rabies is sort of true, though; the species is a natural reservoir for the virus, and if a bat's found in somebody's living space it's standard protocol to treat them for rabies just in case, especially since it's possible for a bat to bite you without you noticing, particularly if you're intoxicated or asleep. Only about 0.5% of bats in the United States actually have the rabies virus, but the small yearly number of human cases in the country can mostly be divided into people who got bitten by mad dogs and people who got bitten by infected bats.

This trope also applies when one or more bats accidentally get into a house or similar place that is not their usual habitat and cause havoc. If someone spooks one or more bats in their lair, that would be Bat Scare.

This is not Goddamned Bats (which is about any kind of annoying video game enemy), but the two categories frequently overlap.

See Good Wings, Evil Wings; evil wings tend to be batlike, while good wings are usually more feathery.

Not to be confused with the baseball kind of bat or the album by Meat Loaf (though the cover art does contain an example). Super-Trope to Bats Equals Rabies and Bloodsucking Bats.

Examples