bloodsucker

Short definition from Wiktionary

Noun

1. 1
   An animal that drinks the blood of others, especially by sucking blood through a puncture wound; a hemovore.
2. 2
   Any parasite.
3. 3
   Any mosquito, gnat, midge, or other small bug which consumes human blood.
4. 4
   One who attempts to take as much from others as possible; a leech.
5. 5
   A vampire.
6. 6
   The changeable lizard (Calotes versicolor).