Jeremiah P. Thomas (October 30, 1830 – December 15, 1885) was an American bartender who owned and operated saloons in New York City. Because of his pioneering work in popularizing cocktails across the United States as well, he is considered "the father of American mixology". In addition to writing the seminal work on cocktails, Bar-Tender's Guide, Thomas displayed creativity and showmanship while preparing drinks and established the image of the bartender as a creative professional. As such, he was often nicknamed "Professor" Jerry Thomas.

Thomas was born about 1830 in Sackets Harbor, New York. (His 1885 obituary in the New York Times said 1832.) As a young man, he learned bartending in New Haven, Connecticut, before sailing for California during its mid-19th century Gold Rush. While in California, Thomas worked as a bartender, gold prospector and minstrel show manager. According to his 1885 obituary, he was left some money by his father, which helped in these travels.

Thomas moved back to the East Coast in 1851, settling in New York City. He opened a saloon below Barnum's American Museum; it would be the first of four saloons he would run in New York City over his lifetime. After running this first bar, Thomas went on the road for several years, working as the head bartender at hotels and saloons in St. Louis, Missouri; Chicago, Illinois; San Francisco, California; Virginia City, Nevada; Charleston, South Carolina; and New Orleans, Louisiana. At one point he toured Europe, carrying along a set of solid-silver bar tools. He was well known for his showmanship as a bartender; he developed elaborate and flashy techniques of mixing cocktails, sometimes while juggling bottles, cups and mixers. He often wore flashy jewelry and had his bar tools and cups embellished with precious stones and metals. At the Occidental Hotel in San Francisco, Thomas was earning $100 a week—more than the Vice President of the United States.

In 1862, Thomas finished Bar-Tender's Guide (alternately titled How to Mix Drinks or The Bon-Vivant's Companion), the first drink book ever published in the United States. The book collected and codified what was then an oral tradition of recipes from the early days of cocktails, including some of his own creations; the guide laid down the principles for formulating mixed drinks of all categories. He would update it several times in his lifetime to include new drinks that he discovered or created. The first edition of the guide included the first written recipes of such cocktails as the Fizz, Flip, Sour and variations of the earliest form of mixed drink, Punch. The 1876 edition included the first written recipes for the Tom Collins, which appeared just after The Tom Collins Hoax of 1874, and one of the earliest known recipes for the Brandy Daisy.

From "IMBIBE !" by David Wondrich:

The fortunes of Thomas' book were likely affected by the Professor's next move: rather than stay at the Occidental (SF), where he could have passed the volume along to the steady stream of clay-moistening literati who stopped in at his bar, he pulled up stakes yet again and headed east to witness the vast and vulgar spectacle that was unfolding 200 miles away in Virginia City, Nevada where a city of 30,000 had sprung up overnight on top of the massive mountain of silver known as the Comstock Lode. By 1864, Thomas was there, either (as local legend has it) at the famous Delta Saloon or at the Spalding Saloon on C Street, where the city directory found him- or, of course, at both.

Nunc Est Bibendum

Head Bartender at the Delta Saloon in 1863 was Prof. Jerry Thomas, most celebrated barman in American history. Coming to Virginia City, according to the Territorial Enterprise** of that year, from the Occidental in San Francisco, he did much to elevate the tastes and drinking habits of the then uncouth Comstock.