Elim Garak
Elim Garak was a Cardassian tailor and Promenade shopkeeper of Garak's Clothiers who lived on the space station Deep Space 9. Garak was a former operative in the Cardassian Obsidian Order but was exiled to Terok Nor following a fall from grace with his mentor, and father, Enabran Tain.
During his time as an operative, Garak was instrumental in the arrest and execution of Gul Dukat's father. He also spent time on Romulus, posing as a gardener at the Cardassian embassy and was rumored to have been involved in several assassinations there. Following his betrayal of Tain, Tain ordered him killed but Garak escaped and was exiled from his homeworld of Cardassia Prime.
Garak kept contacts in the Cardassian Union after his exile, and when Starfleet took control of Deep Space 9, he attempted on occasion to use his experience and his position as the only Cardassian still aboard to regain his usefulness. He was involved in the apprehension of Tahna Los, the escape of several important members Cardassian Underground in 2370, and the return of an abducted Major Kira. Garak also worked with Starfleet during the Dominion War and returned to Cardassia Prime after the Battle of Cardassia.