A donor in general is a person that donates something voluntarily. Usually used to represent a form of pure altruism but sometimes used when the payment for a service is recognised by all parties as representing less than the value of the donation and that the motivation is altruistic.

Often the word is used as a short for:

• Blood donor
• Electron donor — (by analogy) a technical term in chemistry and semiconductor physics (see also the next entry)
• Acceptor (semiconductors)
• Organ donor
• Sperm donor
• Charitable donor
• Egg Donor

In literature:

• Donor (fairy tale) is a stock character of fairy tales