William Hartman or William Hartmann may refer to:
Hartman William Coleman Hartman Jr. (1915–2006), American football player William G. Hartman (born 1938), West Virginia politician William J. Hartman, U.S. Army general and acting director of the National Security Agency Billy Hartman (born 1957), Scottish actor Meteos (gamer) (William Hartman), American professional League of Legends player
Hartmann William Kenneth Hartmann, planetary scientist and author at the Planetary Science Institute William M. Hartmann (born 1939), physicist, psychoacoustician at Michigan State University