Bat

A bat is a nocturnal animal found on Earth that is feared by some humans for the thought that they drink blood, but only some sub-species of bats do, in fact, drink blood.

Many Vampire legends tell of Vampires turning themselves into bats and back into their true forms.

The Tetraps resemble bats in their appearance, and they also sleep upside down just like bats. (DW: Time and the Rani)