Martin "Marty" O'Donnell (born May 1, 1955) is an American composer known for his work on video game developer Bungie's series, such as Myth, Oni, and Halo. O'Donnell collaborated with his musical colleague Michael Salvatori for many of the scores; he has also directed voice talent and sound design for the Halo trilogy. O'Donnell was Bungie's Audio Lead until April 11, 2014.

O'Donnell began his music career writing television and radio jingles as well as scoring for radio and film. O'Donnell moved to composing video game music when his company, TotalAudio, did the sound design for the 1997 title Riven. After producing the music for Myth II, Bungie contracted O'Donnell to work on their other projects, including Oni and the project that would become Halo: Combat Evolved. O'Donnell ended up joining the Bungie staff only ten days before the studio was bought by Microsoft, and would be the audio director for all Bungie projects until he was fired.