Doctor Who is a British science fiction television programme produced by the BBC. The programme depicts the adventures of a mysterious alien time-traveller known as the Doctor who travels in his space and time-ship, the TARDIS, which normally appears from the exterior to be a blue 1950s police box. With his companions, he explores time and space, solving problems, facing a variety of foes and righting wrongs. The show is a significant part of British popular culture. The show's protagonist, the Doctor, has been played by ten actors over the history of the show so far. The different portrayals are often treated as distinct characters. The Doctor is currently portrayed by Matt Smith.