Whose Line Is It Anyway? (often known as simply Whose Line?) is an American improvisational comedy show, which was originally hosted by Drew Carey on ABC and ABC Family and ran from August 5, 1998 to December 15, 2007. A revival of the show, hosted by Aisha Tyler, began airing on The CW on July 16, 2013.
The series is an official adaptation of the British show of the same name and features Ryan Stiles, Colin Mochrie, and Wayne Brady as its regular performers with the fourth seat occupied by a guest panelist. All three regulars appeared on the British series; Stiles and Mochrie were both regulars (first appearing in the second and third series' respectively, and both appearing in every episode from series 8 onwards), with Brady a frequent guest in the final series which moved production from London to Hollywood. Ryan Stiles is the most prolific performer in the history of Whose Line?, having made 76 appearances in the British version, and only having missed two episodes since the start of the run in the U.S. Colin Mochrie is the only performer to have appeared in every episode of the U.S. version of the show.