Keith Giffen is an American writer and artist of comic books.

Giffen is best-known for his long runs illustrating and later writing the futuristic superhero team book Legion of Super-Heroes in the 1980s and 1990s, and for co-creating the humorous, international version of the Justice League in the late 1980s. He is also co-creator, with Roger Slifer, of the alien mercenary Lobo.

He has also worked on titles including All-Star Comics, Ambush Bug and T.H.U.N.D.E.R. Agents.