Cygnia Minor was a planet in Federation space.

In 2266, an Earth colony on Cygnia Minor was facing famine. Doctor Thomas Leighton, a scientist living on a colony on the nearby Planet Q, sent a signal to the starship Enterprise, claiming to have discovered an extraordinary new synthetic food which would end the crisis on 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 Captain Kirk that he had found Kodos the Executioner. (TOS: "The Conscience of the King")