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.

The Micronauts are comic books featuring a group of characters based on the Mego Micronauts toy line. The first title was published by American company Marvel Comics in 1979, with both original characters and characters based on the toys. Marvel published two Micronauts series, mostly written by Bill Mantlo, until 1986, well after the toy line was cancelled in 1980. In the 2000s, Image Comics and Devil's Due Publishing each briefly published their own Micronauts series. Byron Preiss Visual Publications also published three paperback novels based on the Micronauts. In 2016, IDW Publishing published a new comic book series. A live-action film version of the Micronauts was in development by Hasbro Studios and Paramount in 2015. In May 2023, Marvel re-acquired the licensing rights to publish The Micronauts.