Henderson being held prisoner at Camp Gitchie Goomee Noonee Wa-Wa.
Non-speaking CONTROL agent usually seen at the end of a mission taking the prisoners away [e.g. Episode #105: "Absorb the Greek"].
Henderson is himself one of the agents kidnapped by KAOS and held prisoner at Camp Gitchie Goomee Noonee Wa-Wa [Episode #111: "The Not-So-Great Escape, Part 1"], and is memorably seen assisting Larabee hoisting Maxwell Smart onto a coat-hook on his wedding night to ensure that Max remains upright while a map of the Melnick Uranium Mines appears as a rash on his chest [Episode #95: "With Love and Twitches"].
Henderson is not always portrayed by the same actor but in all cases they remain uncredited.