Oliver Callahan was an American animator, having worked primarily for Hanna-Barbera.
Callahan died in 2014, at the age 84.
- Scooby-Doo, Where Are You! - animation (season 1) (credited as Oliver E. Callahan)
- The New Scooby-Doo Movies - animation (season 1) (credited as Lefty Callahan)
- The Scooby-Doo Show - animation (season 1) (credited as O.E. Callahan)
- Laff-a-Lympics - animator (season 1)
- The New Scooby and Scrappy Doo Show - animation (season 1) (credited as Lefty Callahan)
- The 13 Ghosts of Scooby-Doo - animation (season 1)
- A Pup Named Scooby-Doo - animation director (season 1)
- Scooby Goes Hollywood - song sequences directed by, animation
- Scooby-Doo Meets the Boo Brothers - animation director
- Scooby-Doo and the Ghoul School - animation director
- Oliver Callahan at IMDb