Don't call me barkeep. I'm not a barkeep. I'm your host, the proprietor. A sympathetic ear to the wretched souls who pass through these portals.
And a man who will exploit any vice you may have. Two synthales, barkeep.
The bartender's life is a lonely one."
bartender (or barkeep or barmaid) was someone generally employed by a drinking establishment to serve drinks, generally alcohol, behind a bar.
1881, Ed was the bartender of the one saloon in Tombstone, Arizona. ( : " TOS ")
Spectre of the Gun
Dixon Hill stories, written in the 1930s, featured at least two bartenders that Dixon Hill often visited to learn of the whereabouts of certain criminals. One was named Rex who ran his own self-named bar and enthralled Lwaxana Troi; another squealed on Nicky the Nose. ( : " TNG "; Manhunt )
Star Trek: First Contact
2152, Captain Jonathan Archer and Lieutenant Malcolm Reed met a barkeep on a pre-warp planet prior to Lieutenant Reed's cultural contamination. ( : " ENT ")
2153, the crew of the discovered a group of Enterprise Humans who had taken over a Skagaran colony. The barkeep of the local saloon had some Skagaran slaves, such as Draysik. ( : " ENT ")
2254, Doctor Phil Boyce told Christopher Pike that a man will tell his bartender things he'll never tell his doctor when he gave him an iced martini. ( : " TOS ")
There was a bartender on
Argelius II during the " Redjac murders" in 2267. ( : " TOS ")
Wolf in the Fold
2268, Cyrano Jones attempted to sell Antarean glow water, Spican flame gems, and tribbles to a bartender on Deep Space K-7. The bartender wisely declined. Unfortunately, his bar became overwhelmed with the tribbles when they bred and multiplied later on. ( : " TOS "; The Trouble with Tribbles : " DS9 ")
Trials and Tribble-ations A bartender met by one of the hosts of Dax introduced it to a beverage known as a black hole. ( : " DS9 ")
Playing God Guinan worked as the barkeep for the Ten Forward lounge on the USS from Enterprise-D 2365- 2371 at the personal request of Captain Jean-Luc Picard. ( )
Star Trek: The Next Generation
Quark was the eponymous owner and bartender of Quark's on Terok Nor (and later Deep Space 9) for at least thirteen years in the 2360s and 2370s. Quark operated the bar through the latter years of the Cardassian Occupation of Bajor, the Cardassian withdrawal, Federation administration of the station, and the Dominion War. Other employees of Quark's also tended the bar, including Rom, Broik, and Leeta. ( ) However, Quark disliked the term "barkeep"; Star Trek: Deep Space Nine Miles O'Brien once called him a "barkeep", much to Quark's irritation. ( : " DS9 ")
In the script for : " DS9 " Quark names himself a "barkeep" when talking to Meridian Kira Nerys about being his one millionth customer. In the episode's dialog it was changed to "bar owner". 
2372, a Kazon bartender worked on the planet Sobras. He informed Neelix where Jal Tersa was sitting. ( : " VOY ")
2374, Orion Syndicate sympathizer Graife worked as a bartender on Farius Prime. ( : " DS9 ")
Honor Among Thieves