Characters (or Two Characters) is a game that was exclusive to the British edition of Whose Line Is It Anyway. It can be considered a cousin of Explanations and Couples.
Jim Meskimen and Chris Smith played this game in its only television apperance. The premise was that the two would act out the scene, as two characters, which would be expected. Jim was Captain Kirk, and Chris was Mr. Spock.
It was played many times on the radio show, however. Unlike the television playing, though, the improvisors got to choose their own characters.