The Iach'tui are a species from Iach'tui Prime.
The Iach'tui invaded Draqqana in 2261 and conquered the Draqqi people, establishing several labor camps for Draqqi prisoners. After the occupation ended in 2267, a Dopterian ambassador convinced the Draqqi to start a peace process with the Iach'tui. James T. Kirk and the crew of the USS Enterprise later became involved when an Iach'tui began murdering Draqqi individuals, although an investigation by Kirk and Orisa Jilain established that the murdered Draqqi had been informants for the Iach'tui. (TOS - Enterprise Logs short story: "The Avenger")