Aydan

Aydan (or Aydon) 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. He framed Ian Chesterton for the theft, stole the key and hid it.

Aydan 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. (TV: The Keys of Marinus)

Behind the scenes
Aydan's name is spelt "Aydon" in Doctor Who and the Keys of Marinus.