The Awakening (in-universe)

The Malus was a character in The Awakening, a story from Earth-33⅓. A man once spotted who he believed to be the actor who portrayed the Malus on a bus and eventually confronted him to confirm his suspicions. (COMIC: Doctor Who? 172)

Behind the scenes
Although not elaborated upon in the narrative, The Awakening is a Fifth Doctor television story.