Cardassians appear in the Star Trek series. Cardassians are reptilian in looks and they have a military government who at the start of the war against the Dominion were sided with the United Space Federation. They swapped their allegiance to the Dominion when they thought the Dominion would win. Some Cardassians stayed loyal to the Federation such as Elim Garak.
The Cardassians used to own and run Deep Space Nine before it was handed over to the Federation. Even though the Federation run and maintain the spaceship, there are a few Cardassians who frequent the base a lot such as Gul Dukat. The Cardassians had used the station to watch over Bajor which they had enslaved the planet's inhabitents. The Cardassian homeworld is Cardassia Prime.