Aydan

Aydan was a guard in the city of Millennius on Marinus and the husband of Kala.

Biography
Aydan, Kala, and Eyesen conspired to steal one of the keys to the Conscience of Marinus. Aydan was the one who murdered Eprin, framed Ian Chesterton for it, and stole the key and hid it. He was exposed by the First Doctor at Ian's trial, but was shot and killed by Kala to prevent him from revealing his accomplices' identities. (DW: The Keys of Marinus)