John Ratzenberger

From Pixar Wiki

John Ratzenberger has performed the voice of a character in every feature-length Pixar film to date. His roles have included:

• Hamm in Toy Story, Toy Story 2 and Toy Story 3
• P.T. Flea in A Bug's Life
• the Abominable Snowman in Monsters, Inc.
• the Moonfish school in Finding Nemo,
• the Underminer in The Incredibles,
• Mack in Cars and Cars 2
  • In the end credits of Cars, Ratzenberger gave voice to the Hamm car, the Abominable Snowplow, and the P.T. Flea car
• Mustafa in Ratatouille
• John in WALL•E
• Construction Foreman Tom in Up

He is, however, probably most famous for his Emmy-nominated role as Cliff Clavin on the television series Cheers.