Bactrican

Bactricans are a civilization native to the planet Bactrica. Bactricans 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 Bactricans, known as "thirds", are neither male nor female, but are necessary to enable the procreative process (see Bactrican Triad). (DS9 - The Lives of Dax short story: "The Music Between the Notes")