The official Doctor Who site has confirmed that the Sontarans, potato-headed monsters from the classic series, will return to Doctor Who in Series Four.
The Sontarans, a militaristic clone race, first appeared opposite the Third Doctor and Sarah Jane Smith in 1973, in The Time Warrior, which has recently been released on DVD in the UK. Sontarans also appeared in The Sontaran Experiment (1975), The Invasion of Time (1978) and The Two Doctors (1985). More recently, the potato-headed monsters were mentioned in "The Eye of the Gorgon, Part 1", an episode of The Sarah Jane Adventures which aired on CBBC on Monday.
In Series Four, the Sontaran leader will be played by Christopher Ryan, best known as Mike in the 1980s comedy series The Young Ones. Ryan appeared as another alien, the Mentor Lord Kiv, in the 1986 story The Trial of a Time Lord: Mindwarp, opposite Sixth Doctor Colin Baker. That story also featured Trevor Laird, who played Martha Jones' father Clive in Series Three.