Quark was a male Ferengi on Star Trek: Deep Space Nine.
The son of Ishka and Keldar, Quark traveled to Terok Nor with his brother Rom and nephew Nog to run a bar on the station. They remained as the Cardassians withdrew and the Federation took over, renaming the station Deep Space Nine.
Quark's Bar became the center of station life on DS9. Quark for his part participated in all manner of activities, some of which were less than legal. Even so Quark had his standards and there were some things even he would not stoop to. His time in the Federation led to his developing a sense of ethics that some of his fellow Ferengi lacked.
Quark had a rivalry with Odo that went on from the moment Odo became chief of security on DS9. Odo spent a great deal of his time short circuiting Quark's schemes and arresting Quark when he broke the law. Despite this the two men respected each other. He also was attracted to Major Kira Nerys, but she firmly put a stop to his obscene advances. Quark also nursed an attraction to Jadzia Dax. While she was a bit more tolerant of Quark, she did not feel anything beyond friendship for the Ferengi bartender.
Even though Quark often acted like a jerk towards his family and friends, in reality Quark deeply cared for his brother, nephew, mother, and his friends.
Quark bore a strong resemblance to the Ferengi DaiMon Letek, leading Dax to quip that Letek looked familiar when the DS9 crew encountered him in the 2370s.
When the Federation was forced to leave DS9 at the onset of the Dominion War, Quark remained on the station. At first content to continue his business under the new regime, he came to see how evil the Dominion was, and joined Major Kira's resistance movement. He helped break Kira, his brother, Jake, and the others out of captivity in order to buy Benjamin Sisko time to enter the wormhole and convince the Prophets to intervene against the Dominion reinforcements travelling through the wormhole.
Quark remained on the station throughout the Dominion War and remained on board following the war. At the end of the war he was running a pool on who would be the next Kai of Bajor, something Kira Nerys quickly put a stop to.