James Arthur "Jamie" Madrox, also called the Multiple Man, is a fictional character, a Marvel Comics superhero, associated with the X-Men. Created by writer Len Wein with script from Chris Claremont and art by John Buscema, he first appeared in Giant-Size Fantastic Four #4 (February 1975).

A mutant with the ability to create instant duplicates or "dupes" of himself, Madrox was largely a minor or supporting character until his appearance in the 1987 miniseries Fallen Angels. The character underwent greater development under writer Peter David through his appearance in David's run of the monthly series X-Factor (vol. 1) in the 1990s, and in David's second and ongoing run of the title (vol. 3) in the 2000s.