Karl (The Ultimate Adventure)

 was a mercenary employed by the Dalek Emperor to capture the American Envoy with the help of the Cybermen. She tricked the Sixth Doctor into going to Altar III instead of following them to the Dalek flag ship. He also managed to get the Doctor away from Bar Gallactica, before the Daleks lost him. After the Daleks betrayed him and killed Madame Delilah he helped the Doctor defeat them. (AUDIO: The Ultimate Adventure)