Gallifrey is a fictional planet in the long-running British science fiction television series Doctor Who. The planet is home to both the Doctor, and others of his race, the Time Lords. It is supposed to be located in the constellation of Kasterborous, at "galactic coordinates ten-zero-eleven-zero-zero by zero-two from galactic zero centre", some 250 million light years away from Earth. During the first decade of the television series, the Doctor's home planet was not identified by name. The name was first used in the 1973 serial The Time Warrior.

It is never definitively stated "when" the appearances of Gallifrey in the television series take place. As the planet is often reached by means of time travel it could conceivably exist anywhere in the past or future relative to our present. The spin-off novels seem to take the stance that Gallifrey is in the relative past.