H'atoria was a Klingon Empire planet, near the Federation border. The world sustained a small Klingon colony population in the 24th century. H'atoria was mostly covered in water oceans, with very few landmasses, and had two small moons. H'atoria was home to a native amphibious civilization called the Selsseress.
In early 2381, it was one of the many worlds devastated by the Borg Invasion. Over seven thousand Borg cubes launched to the Alpha and Beta Quadrants from the Azure Nebula. While briefing Federation President Nanietta Bacco on their losses, Raisa Shostakova estimated that H'Atoria was likely to be attacked within four hours. The Borg assaulted H'atoria, 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 - Destiny novel: Mere Mortals)