Bartender

A “bartender” (also “bar-tender” or “bar tender”) is someone who “tends” to or serves drinks at a “bar.” Other names for this job include “barkeeper” (or “bar keeper”), “barman” (or “bar man”) and “mixologist.”
 
“Bar-tender” is cited from 1809 in a New Jersey newspaper.
 
 
Wikipedia: Bartender
A bartender (barman, barkeeper, barmaid, mixologist, tapster among other names) serves beverages behind a bar in a bar, pub, tavern, or similar establishment. This usually includes alcoholic beverages of some kind, such as beer (both draft and bottled), wine, and/or cocktails, as well as soft drinks or other non-alcoholic beverages. He/She “tends the bar”. A bartender may own the bar they tend or be simply an employee. Barkeeper carries a stronger connotation of being the purveyor i.e. ownership. In addition to their core beverage-serving responsibility, bartenders also:

. take payment from customers (and sometimes the waiters or waitresses);
. maintain the liquor, garnishes, glassware, and other supplies or inventory for the bar (though some establishments have barbacks who help with these duties);
 
In establishments where cocktails are served, bartenders are expected to be able to properly mix hundreds to thousands of different drinks.
 
Merriam-Webster Dictionary
Main Entry: bar·tend·er
Pronunciation: \ˈbär-ˌten-dər\
Function: noun
Date: 1836
: a person who serves drinks at a bar
     
(Oxford English Dictionary)
bartender
orig. U.S.
[f. BAR n.1 + TENDER n.1]
a. A keeper or manager of a refreshment bar.  b. A bar-attendant or barman.
1836 Franklin Repository (Chambersburg, Pa.) 5 Apr. 3/3 My bar-tender..has become a drunkard according to the course of trade.
1864 G. A. SALA in Daily Tel. 21 Nov., The bar-tender is a person of great gravity of countenance.
1876 J. HARTLEY Seets i’ Lundun iv. 53 Aw axed th’ bar~tender if he’d onny.
1884 Fortn. Rev. Mar. 389 A bar-tender in..this low groggery.
1961 Spectator 11 Aug. 199 A dish-washer and part-time bartender.
1968 Globe & Mail (Toronto) 17 Feb. 51 (Advt.), Bartender, for dining lounge.
 
25 September 1809, Federalist (NJ), pg. 3:
To Thomas M. Davenport, Esq. Justice, Judge, Innkeeper, Bar-Tender &c. &c
 
22 November 1814, Boston (MA) Daily Advertiser, pg. 4 ad:
Bar Tender.
A YOUNG MAN of good habits can find employment at the Concord Hotel as Bar Tender. Inquire of the subscriber or at this office.
JAMES HAMILTON.
Concord, Nov. 9th, 1814.
     
15 November 1815, Massachusetts Spy (Worcester, MA), pg. 1 ad:
A Bar-Tender
WILL find good encouragement, by applying at the HOTEL, in CONCORD, of the Subscriber.
JAMES HAMILTON
Concord, Nov. 7, 1814.
 
18 March 1818, Massachusetts Spy (Worcester, MA), pg. 1 ad:
Bar-Tender wanted.
WANTED—aa trusty, active MAN to tend Bar.—A person of this description will obtain good wages by applying to
JAMES HAMILTON.
Concord, March 9, 1818.
 
27 January 1827, Farmer’s Cabinet (NH), pg. 2:
And when I step in of an errand, and see the bar-tender, under the eye of his employer, dealing out sling and bitters to persons who have already taken twice as much aboard as they can safely carry without foundering, I go away saying to myself, nobody here—works it right.
     
23 February 1829, Watch-Tower (New York, NY), pg. 3:
Fatal Sport.—On Sunday last, as we are informed, a man named Marsh, a resident of the village of Lewistown, in this county, was killed in a public house at that place, by a blow on the breast, given him in sport, for a wager of a glass of liquor, by a young man acting as bar tender in the house.
 
15 May 1830, Saturday Evening Post, pg. 2:
He stated in his defense that the liquor was sold contrary to his orders by his bar tender; who has since been discharged his service.