Vampire Bats
This species is the reason bats have a bad reputation. They are native mainly to Latin America although they prefer a smaller meal with the taste of blood, they will attack a human wandering in their area at night.
They are also the only species that can walk. Once the Vampire bat bites its prey, some of their special saliva prolongs the bleeding so they can feed of it for a longer period of time, stopping the blood from clotting.