Quark is a fictional character in the American television series Star Trek: Deep Space Nine. He was played by Armin Shimerman and is a member of the extraterrestrial race known as the Ferengi, who are stereotypically capitalist and motivated only by profit.

Quark was introduced on television in 1993, in the two-part Star Trek: Deep Space Nine premiere "Emissary".

Talking about his depiction of Quark, Shimerman said the character developed significantly during the start of the sixth season of Deep Space Nine, during a story arc in which the Dominion took control of the Deep Space Nine station:

He soon learns that although things may appear to be good under Dominion rule and life is pretty good, they still don't have liberty, and you've got to fight for it. Quark was one of those deluded people who thought, 'This is fine — we all get to do what we want to do,' and didn't realize that liberty was more important than creature comforts. ... Like any Everyman character in literature, Quark has to go through some turmoil before he realizes the truth.

Max Grodénchik, who was cast as Quark's brother Rom, originally auditioned for the role of Quark; he later said, "I got to know Armin a bit during the audition process. He had so much more history with the show."

Karen Westerfield did the makeup for Quark during all of Star Trek: Deep Space Nine. Shimerman said, "I always say that Karen helped create Quark as much as I did". He also said of Westerfield, "It was her idea to put the maroon shading around my eyes. The makeup accented the eyes, so you could see the eyes better. The other Ferengi characters didn't have that, and it made a huge difference."

Before opening a bar, known as "Quark's Bar, Grill, Gaming House and Holosuite Arcade", Quark served as a cook aboard a Ferengi freighter for eight years, according to the Star Trek: Deep Space Nine episode "Profit and Loss". According to his own admission, he was rising to the top of the Ferengi business world as an assistant to the Grand Nagus until he made the mistake of having sex with his boss's sister which resulted in him becoming a cook. He came to the station while it was named Terok Nor during the Cardassian occupation of Bajor. Originally, Quark admired the Cardassian race for their version of morality, but later he seemed to take pity on the downtrodden Bajoran people, selling them food and equipment just above cost, which could have gotten him into serious trouble if the Cardassians had found out. When the station changed hands at the end of the occupation, he decided to leave. Commander Sisko, feeling that Quark's Bar (which offered holosuites and gambling) would encourage commercial tourism to boost the station's economy, extorted Quark into staying, using Quark's nephew Nog as a bargaining chip, in the Deep Space Nine pilot episode, "Emissary."

Quark engages in a variety of shady deals, but neither Sisko nor Odo, Quark's nominal nemesis and head of station security, take serious action against him, partially because his value outweighs his numerous illegal activities, which for the most part harm no one. Furthermore, the station's status as, technically, the property of Bajor and thus only nominally a Federation station, sometimes prevented Sisko from prosecuting Quark to the full extent of Federation law; Sisko was not allowed such latitude with criminals who were also Federation citizens, such as his own lover, Kasidy Yates, whom Sisko was once obliged to arrest for dealing in illicit replicators when, on the same occasion, he was obliged to allow Quark relative amnesty for dealing in illicit weapons. In the episode "Business as Usual", Sisko admits that he had "cut [Quark] a lot of slack in the past [and] even looked away once or twice when [he] could have come down hard." However, Sisko's leniency does not stop Odo from regularly interfering with Quark's illegal doings. A shrewd businessman, Quark often quotes the Ferengi Rules of Acquisition. In one episode, "Civil Defense", when Quark and Odo are trapped in Odo's office as Deep Space Nine is about to explode, Quark mourns the fact that despite a lifetime of plotting and faithfully following the Rules of Acquisition the only thing he owns is a bar; Odo tries to cheer Quark up by saying that although he has known of Ferengi who are richer than Quark, Quark is the most devious Ferengi Odo has ever met.