Doctor Who: Meglos, Episode 2 (1980)

In the second episode of the four-part Meglos, the title character (Christopher Owen) is determined to restore his past glories as the ruler of the now-extinct Zolfa-Thuran civilization. To do this, Meglos kidnaps the Doctor (Tom Baker) and assumes his identity, the better to tap the precious power sources of the planet Tigella. Jacqueline Hill, who'd played the Doctor's traveling companion Barbara Wright in the earliest episodes, guest stars as Lexa, leader of the cultish Deon race. Written by John Flanagan and Andrew McCullough, "Meglos, Episode 2" first aired on October 4, 1980. ~ Hal Erickson, All Movie Guide