The hairy-legged vampire bat is one of three extant species of vampire bats. It mainly feeds on the blood of wild birds, but can also feed both on domestic birds and humans. This vampire bat lives mainly in tropical and subtropical forestlands of South America, Central America, and southern Mexico. It is the sole member of the genus Diphylla.

Vampire bats, members of the subfamily Desmodontinae, are leaf-nosed bats currently found in Central and South America. Their food source is the blood of other animals, a dietary trait called hematophagy. Three extant bat species feed solely on blood: the common vampire bat, the hairy-legged vampire bat, and the white-winged vampire bat. Two extinct species of the genus Desmodus have been found in North America.