Gamma Hydra (or Gamma Hydrae) was a star in the Gamma Hydra sector of Federation space, near the Romulan Neutral Zone. The Gamma Hydra system had at least four planets. (TOS episode: "The Deadly Years") The comet Icarus IV also orbited Gamma Hydra. (ST reference: Star Charts) The USS Enterprise visited the Gamma Hydra system en route to Starbase 10 in 2267. (TOS episode: "The Deadly Years")