Bats did not tie to vampires until the nineteenth century, but they have been used in fables and stories since Aesop and his fables. Bats have been seen with likeness to humans, such as how babies nurse from a female bat’s pair of breasts.
In the Middle Ages, they became associated with the Christian devil, and were often believed to be signs of death if not the agent of death.
The Spanish conquistadors interpreted a type of bat found in Mexico and South America that was considered a blood sucking creature. Over the next few centuries, the associations of bats and vampires grew.
It wasn’t until 1897 when Dracula was published when bats and vampires were without-a-doubt linked. A bat appears outside of Jonathan Harker’s window at Castle Dracula. Later in the story, Harker sees Dracula assume bat-like characteristics.
With the popularization of vampires post-WW2 West, the bats became one of the most commonly used image in horror movies.