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H'atoria was a small Klingon colony world near the Federation border. It was mostly covered in oceans, with very few landmasses, and had two small moons. H'atoria was home to a native amphibious species called the Selsseress.

In early 2381, it was one of the many worlds devastated by the Borg attack, leaving virtually nothing behind, only a few surviving Selsseress. About three months later, the abandoned world was conquered by the Kinshaya, as part of the new offensive against the Klingon Empire. (ST novel: A Singular Destiny)

In an alternate future timeframe created by Q, Worf was governor of H'atoria in 2395. (TNG episode & novelization: All Good Things...)