S'ti'ach'aas, also known as S'ti'ach, was a class M planet, homeworld of the S'ti'ach, and, by the late-24th century, a Federation member planet. (TTN novels: Orion's Hounds, Sword of Damocles)

S'ti'ach'aas was an ocean world, with only limited land and resources on islands. The planet also had hyper-gravity, which coupled with limited room prompted life on S'ti'ach'aas to evolve to be relatively small and compact. The dominant, and predatory, S'ti'ach species featured a dense bone structure to help them resist the planet's gravity, but their anatomy was otherwise low density to keep their weight down and provide a cushioning effect should they fall. (TTN novels: Orion's Hounds, Sword of Damocles, Over a Torrent Sea)