Bleeder

noun

1. A person who is easily made to bleed, or who bleeds in unusually large amounts, particularly a hemophiliac.
2. A blood vessel that requires cauterization etc. to stop it from bleeding during surgery.
3. Anything that saps a resource produced by something else.
4. A valve designed to release a small amount of excess pressure from a system.
5. A troublesome fellow; a blighter.