indian giver an offensive term for someone who asks you to return a present he has given you
altruist,
philanthropist someone who makes charitable donations intended to increase human well-being
settlor,
trustor (law) a person who creates a trust by giving real or personal property in trust to a trustee for the benefit of a beneficiary; a person who gives such property is said to settle it on the trustee
contributor,
subscriber a writer whose work is published in a newspaper or magazine or as part of a book
donor -
(medicine) someone who gives blood or tissue or an organ to be used in another person (the host)
benefactor,
helper a person who helps people or institutions (especially with financial help)
medical specialty,
medicine the learned profession that is mastered by graduate training in a medical school and that is devoted to preventing or alleviating or curing diseases and injuries; "he studied medicine at Harvard"
blood donor someone who gives blood to be used for transfusions
