Gamma Hydra IV is the fourth planet in the Gamma Hydra star system, the location of a Federation settlement at Johnson City. The original settlers of the planet were irradiated by a rogue comet in 2267. (TOS episode: "The Deadly Years") In 2372, Odo disguised himself as a container bound for Gamma Hydra IV, carrying Bajoran Muriniri dolls. (DS9 novel: The 34th Rule)