Falsten

 was the leader of a group of mercenaries that worked for Baron Denton de Kay Leigh. The Seventh Doctor convinced Falsten and his mercenaries to work for him instead. The Eighth Doctor freed Falsten and his men from the Seventh Doctor's control device. In return, Falsten and some of his men helped the Doctor rescue Charley Pollard from the Baron. (PROSE: The Heroine, the Hero and the Megalomaniac)