Guard (The Face of Evil, part 2)

At the start of the Fourth Doctor's ultimately successful run of the Test of the Horda, a Sevateem guard struck Leela across the face to silence her from helping the Time Lord. In response, the Doctor asked Calib what the man's name was. When Calib wondered which man he meant, the Doctor flicked a Horda onto the man's body. The guard ran away with the creature fiercely embedded into his shoulder. (TV: The Face of Evil)