The Hydronians were a reptilian race from the planet Hydra.
The Hydronians were a peaceful, exploring race, until the Larviie Wars began. Eight billion Hydronians died during the war. After the end of the Larviie Wars and the extinction of the Larviie, the Hydronians were split into three communities: the Settlers, who remained on their home planet Hydra and the surrounding sector to rebuild their homes; the Colonists, who left their homes in search of a new beginning, encountering the UFP and the Bayonian Empire and built a mighty and helpful inter-species Alliance; and the Outcasts, who became a group of warring vigilantes attacking pirates, slavers and the Dominion Alliance. The Hydronians were skillful engineers, and their prowess saved many lives.
- Star Trek: The Second Little Wolf – "Beware the Golden Dragon" (First mentioned)
- Star Trek: The Second Little Wolf – "The Battle of the First Blood, Part I" (First appearance)
- Star Trek: The Second Little Wolf – "The Battle of the First Blood, Part II"
- Star Trek: The Second Little Wolf – "The Mountain Goat and the Ice Demon" (Mentioned only)