Bactrican

Bactricians are a race native to the planet Bactricia in the Alpha Quadrant. Bactricians are humanoid, with facial features similar to humans of Asian descent. While females are typically shorter than males, there is little visible difference between the two genders. A small percentage of Bactricians, known as "Thirds", are neither male nor female, but are necessary to enable the procreative process. (see: Bactrician Triad) (DS9 short story: "The Music Between the Notes")