Jack of Hearts is a fictional superhero appearing in American comic books published by Marvel Comics. The character first appeared in The Deadly Hands of Kung Fu #22, and was created by writer Bill Mantlo and artist Keith Giffen. He starred in his own four-issue mini series and has been a regular character in the Iron Man comics as well as at one point being a regular in The Avengers comic book.

William Timothy Mantlo is an American comic book writer, primarily at Marvel Comics. He is best known for his work on two licensed toy properties whose adventures occurred in the Marvel Universe: Micronauts and Rom, as well as co-creating the characters Rocket Raccoon and Cloak and Dagger. An attorney who worked as a public defender, Mantlo was the victim of a hit-and-run accident in 1992 and has been in institutional care ever since.