<P> At the conclusion of each episode, a winner or several winners were chosen arbitrarily by Carey . The "prize" was either to play a game with the host, or to sit out while the other performers did so . After this game during the first season of the series, credits simply rolled under the show's theme . In the second season, the reading of the credits was performed by one or more cast members in a comedic fashion, based on a theme announced by Carey that often derived from a successful joke earlier in the show . </P> <P> The show's "short - form" approach to improv received criticism from some improv actors . However, performer Colin Mochrie has stated the show was never intended to be the "be-all and end - all" of improv, but that it was meant to introduce improv to the masses . </P> <P> Like the UK original, the U.S. version of Whose Line Is It Anyway? features four performers, two of whom, Colin Mochrie and Ryan Stiles, were regular, permanent performers throughout the original format, having featured prominently in the UK original; Stiles since his first appearance in its second season in 1989, while Mochrie since his first appearance in the following season in 1991, with both making regular appearances in the UK version from 1995 until its end in 1999 . Another performer who made frequent, recurring appearances was Wayne Brady, who appeared in the majority of episodes of the original format . During his tenure as host, Drew Carey also took part, though only in one game, after one of the performers was declared the "winner" and allowed to take his place at his desk in the studio; host Aisha Tyler did not take part in games when the show was revived, but has occasionally joined in for a quick scene during the Scenes from a Hat game . As of 2017, Mochrie is the only performer to have appeared on every single episode of the American version . </P> <P> Alongside Mochrie and Stiles, other veterans of the UK series appeared on the U.S. version included Greg Proops, Brad Sherwood, and Chip Esten, with the show introducing several newcomers that took part, including Denny Siegel, Kathy Greenwood, Jeff Davis, Patrick Bristow, Stephen Colbert, Kathy Kinney, and Ian Gomez, though mainly in the early seasons of the show . Unlike the UK original, the US version occasionally featured a celebrity guest performer, such as Robin Williams, Kathy Griffin, and Whoopi Goldberg, while on other occasions, a celebrity made a guest appearance for individual games; such appearance have included Sid Caesar, David Hasselhoff, Florence Henderson, Jerry Springer, Joanie "Chyna" Laurer, Richard Simmons, Katie Harman, Jayne Trcka, the Loyola Marymount University cheerleaders, Hugh Hefner, and Lassie . Celebrity guests became a regular feature of the show beginning with season 9 . </P>

Who's line is it anyway original cast