Marshall Kenneth Kirk (December 8, 1957 – c. July 28, 2005) was a New England Historic Genealogical Society librarian, and a noted writer and a researcher in neuropsychiatry. He is, however, best known as one of the co-authors of After the Ball: How America Will Conquer Its Fear and Hatred of Gays in the '90s, a strategy for the LGBT movement in the 1990s.