Joseph Stacher (c. 1902 – 1977) (alias "Doc Stacher," "Doc Harris," "Joe Rosen", "J. P. Harris," "George Kent," and "Harry Goldman") was a Jewish syndicate leader who helped bring together Jewish and Italian-American organized crime groups into a national organized crime syndicate in the early 1930s. Stacher was later a leading force in organized crime's gambling activities in Las Vegas and pre-Castro Havana.

Joseph Stacher was born Gdale Oistaczer (גדאַלע אויסטאַטשער) (commonly pronounced Gedalia) in Letychiv, Ukraine around 1902. He Americanized his name after emigrating with his family to the United States in 1912.

As a teenager living in Newark, New Jersey Stacher became friends with Abner "Longie" Zwillman. He later joined Zwillman's gang, which went by the name "The Happy Ramblers" and which offered protection to Jewish storeowners and street vendors in Newark's Third Ward who faced harassment by Irish thugs from the neighboring Eighteenth Ward.

Zwillman and Stacher became involved in bootlegging with the advent of Prohibition in 1920. Starting off by providing protection for liquor shipments as they traveled from shoreline drop-off points to their ultimate destination in New Jersey or New York, Zwillman and Stacher ultimately became partners with Joseph Reinfeld as part of the Reinfeld syndicate, which imported nearly 40 percent of all the illicit alcohol consumed in the United States during Prohibition and took in an estimated $60,000,000 during the years from 1926 to 1933. They remained Reinfeld's silent partners in Browne-Vintners, a liquor importing and distribution company, after the end of Prohibition.

Stacher served as Zwillman's lieutenant in other areas and, by the end of the 1920s, was running much of Zwillman's gambling operations. Stacher also provided muscle for Zwillman, as shown by his repeated arrests for assault and battery in 1926 and 1927.

Stacher's bootlegging and gambling activities brought him into contact with Meyer Lansky, with whom he would work for the rest of his career in organized crime. Lansky and Stacher played a pivotal role, along with Charles "Lucky" Luciano, in forming an enduring alliance between Jewish and Italian gangsters.

The 1920s were marked by violent conflicts between members of different organized crime groups for control of territory and rackets in American cities. Those feuds became particularly severe in New York in the late 1920s, culminating in the Castellammarese War that broke out in early 1930 between rival factions of the Italian-American Mafia. At its conclusion in 1931 most of the old leaders had been murdered or sidelined and a new structure, which created a commission to resolve disputes between the Five Families in New York and its environs, as well as other organized crime organizations nationwide and in Canada, had been put in place.

Jewish mobsters such as Lansky and Benjamin "Bugsy" Siegel had established strong alliances with the "Young Turks," such as Lucky Luciano, who emerged as the victors in the Castellammarese War. They had also played a key role at critical moments in that conflict, providing gunmen who were part of the teams that assassinated both Joe Masseria and Salvatore Maranzano.