I would not want to share my home with vampire bat.

The common vampire bat (Desmodus rotundus) is one of only three mammals that feed exclusively on blood.

They swoop down at night to feed on the blood of cattle and other animals, including, occasionally, people.

They make an incision near an artery using their teeth and then lick up the blood as it trickles out.

BBC Science - DNA secrets of how vampire bats became bloodthirsty