His acting credits include 47 productions and an additional 22 notable television appearances. His first role was a Patron in The Ritz (1976), before appearing in minor roles in movies including Firefox; A Bridge Too Far; and Superman II as a NASA controller; Star Wars: Episode V - The Empire Strikes Back (1980) as "Major Bren Derlin"; and Gandhi (1982) as an American Lieutenant.
All of Pixar Animation's feature films include Ratzenberger, who has become something of a "good luck charm" to the studio. John is also a member of Pixar's softball team.
- Hamm the Piggy Bank in Toy Story (1995)
- P.T. Flea the Circus Ring Leader in A Bug's Life (1998)
- Hamm the Piggy Bank in Toy Story 2 (1999)
- Yeti in Monsters Inc. (2002)
- Fish School in Finding Nemo (2003)
- The Underminer in The Incredibles (2004)
- Mack Truck in Cars (2005)
Ratzenberger also hosts the Wildcard section in ATARI's PC game based on the popular board game, Trivial Pursuit.
Recently, John Ratzenberger turned down the role of Hamm for the movie Toy Story 3, and will not be involved unless Pixar is making it.