Mercenary
A mercenary was a soldier who took part in conflicts for private gain. General Grugger led a group of Gaztak mercenaries who worked for Meglos. (TV: Meglos)
As observed by the Third Doctor, the Ogrons served as mercenaries doing the "dirty work" of other species, most notably the Daleks. (TV: Day of the Daleks, Frontier in Space)
The Tenth Doctor took the Judoon to be a mercenary police force. (TV: Smith and Jones) The Thirteenth Doctor identified them as intergalactic mercenaries. (TV: Fugitive of the Judoon)
After the destruction of the Tenth Sontaran Battle Fleet and his defeat on Earth by Sarah Jane Smith, the disgraced Commander Kaagh worked as a mercenary for the Bane. (TV: Enemy of the Bane)
Kane acquired an army of mercenaries to help him get revenge on Proamon. (TV: Dragonfire)
In an introduction that the Master wrote for Doctor Who Magazine, he admitted that his life as the megalomaniac's megalomaniac wasn't all "murder, miniaturisation, and mercenary acts", and did have acts of so-called "charity work", which often involved more murder. (PROSE: A letter from the Master)
