Giuseppe "Joe The Boss" Masseria (1879–April 15, 1931) was an early Mafia don in the United States. Masseria controlled all organized crime in New York City from 1920 until his assassination by Lucky Luciano in 1931 during the Castellammarese War.

After emigrating to the United States in 1903 to avoid murder charges in Sicily, Masseria became an enforcer for the Morello Gang in the Lower East Side of New York City. By 1920, he had assumed command of the gang through a series of assassinations.

Salvatore Maranzano was sent with several other men from Sicily in 1927 to gain control of the American Mafia for Don Vito Cascio Ferro. Maranzano gained the support of a faction and declared war on Masseria, in what became known as the Castellemmarese War.

Masseria was killed on April 15, 1931 by hitmen acting on the orders of his top lieutenant, Lucky Luciano, ending the Castellemmarese War and briefly establishing Maranzano as capo di tutti capi, or "boss of all bosses".

de:Joe Masseria ja:ジョー・マッセリア