In 2266, Doctor Thomas Leighton, an old friend of Captain James Kirk, sent a signal to the Enterprise, informing Kirk that he had discovered an extraordinary new synthetic food, which would end the threat of famine on nearby Cygnia Minor. It was soon discovered, however, that Leighton had lied about the discovery in order to lure the Enterprise to Planet Q to convince Kirk that he had found Kodos the Executioner. (TOS: "The Conscience of the King")
Presumably, Planet Q was located in the Alpha Quadrant.
- Planet Q System: This system was left unnamed. The system was located in or near Federation space. This was a single star system. Primary was a F-class star with a magnitude of +5, which was the same brightness as Sol. ("United Federation of Planets III")