Bloodsucker

Noun

 * 1) One who drinks the blood of others, especially by sucking blood through a puncture wound.
 * 2) By extension, any parasite.
 * 3) By extension, one who attempts to take as much from others as possible.
 * 4) A vampire.

Alternative forms

 * blood-sucker

Thesaurus
barnacle, bedbug, blackmailer, extortioner, extortionist, freeloader, hanger-on, harpy, leech, lounge lizard, moocher, mosquito, parasite, predator, profiteer, racketeer, raptor, scrounge, scrounger, shakedown artist, shark, spiv, sponge, sponger, sucker, tick, vampire, vulture, wood tick