John Dezso Ratzenberger is an American actor, voice actor, director, producer, writer and entrepreneur. He is one of the most successful actors of all time in terms of box-office receipts. Ratzenberger is best known for portraying Cliff Clavin on the popular comedy series Cheers, for which he earned two Primetime Emmy nominations. He is also known being a voice actor appearing in almost every Pixar Animation Studios feature film, including Hamm in the Toy Story franchise, The Underminer in The Incredibles franchise, and Mack in the Cars franchise.