The Cartassians are a client race co-existing with the Romlians on one of Neptune's moons. Although they are closely associated with the Romlians the treaty and the neutral zone do not apply to them. The Cartassian have within the last century turned from a peaceful culture to a warrior culture due to the limited resources on their home planet. In 1941 they invaded Miranda forcing a majority of the Bajaaran inhabitants to flee to Enceladus.
The Cartassians are typified buy their ruthlessness and adherence to duty. This compliance to duty may be motivated by the penalties imposed by the Cartassian secret police for any not in compliance with their orders. The Cartassian home world has a climate similar to Venus with dim light and warm moist atmosphere.