Clifford C. Clavin Jr. (born 1947 or 1949) is a fictional character on the American television show Cheers played by John Ratzenberger. A postal worker, he is the bar's resident know-it-all. Cliff was not originally scripted in the series' pilot episode, "Give Me a Ring Sometime", but the producers decided to add a know-it-all character and Ratzenberger helped flesh it out. The actor made guest appearances as Cliff on The Tortellis, St. Elsewhere, Wings, and Frasier.
Development
thumb|upright=.6|Ratzenberger at the [[44th Primetime Emmy Awards|1992 Emmy Awards]]
Creation
The original script for the 1982 pilot, "Give Me a Ring Sometime", did not include Norm Peterson or Cliff Clavin. George Wendt and John Ratzenberger originally auditioned for a minor character, George, and George Wendt was hired for that role. George was Diane Chambers' first customer, had one line (consisting of the order, "Beer!") and was intended for only one episode.