The real name of vampire bats?

Here's the answer straight from Wikipedia's "Vampire Bat" page:

There are three bat species that feed solely on blood: the Common Vampire Bat (Desmodus rotundus), the Hairy-legged Vampire Bat (Diphylla ecaudata), and the White-winged Vampire Bat (Diaemus youngi). All three species are native to the Americas, ranging from Mexico to Brazil, Chile, and Argentina.