Joseph "Joe The Greaser" Rosenzweig (17 April 1890 – ), also known as Joe Rosen, was an American New York City labor racketeer in the early 1900s as an ally of "Dopey" Benny Fein during the Labor Slugger Wars (1914–1917).
Controlling labor slugging in New York's Lower East Side, Rosenzweig's organization of around one hundred acted mostly as strikebreakers, specializing in breaking up union picket lines, demonstrations and other protests.
With political protection from Tammany Hall, Rosenzweig maintained complete control of strikebreaking and labor slugging well into the early 1910s.
The war ended with Paul's death the following year, when he was killed by Rosenzweig and several gunmen, including Jacob Heiseman, Benjamin Snyder, and Hyman Berthstein.
After he received a warning from ex-lieutenant Waxey Gordon against attempting to reform his gang, he soon left New York retiring from crime thereafter.