Warriors' Gate is the fifth serial of the 18th season in the British science fiction television series Doctor Who, which was written by the English author Stephen Gallagher and first broadcast in four weekly parts from 3 January to 24 January 1981. The serial is the last of three loosely connected serials known as the E-Space trilogy and the last regular to feature Lalla Ward as Romana. John Leeson would return as the voice of K-9, but not as a permanent companion.