River Song is a fictional character in the British science-fiction series "Doctor Who". She is played mainly by Alex Kingston. River Song was first seen in the series as a future companion of the Doctor. The Doctor is an alien Time Lord who travels through time and space in his TARDIS. River Song is a time traveler herself. Because of this, her time spent with the Doctor does not happen in the same order his time with her does. The first time they met (in the series) is his first but her last time. In later episodes, River is a companion of the Doctor in his eleventh form (Matt Smith). River Song was created by "Doctor Who" writer Steven Moffat for the programme's fourth series in 2008. When moffat took over the job of executive producer from Russell T Davies, he started developing the character's background. He created adventures earlier in River's timeline. Alex Kingston went from being from a guest star to a recurring actor in the series. Other actresses have also played younger versions of the character. She has been an infant, a child and a young adult.