A native of New York's lower East Side, Greenwald dropped out of school at age 10 and began selling newspapers in front of the Thalia Theater.
Undeterred, Greenwald joined a repertory theatre company at a salary of $25 per week, part of which went to buy his costumes and wigs.
[2] He eventually progressed from five-times-a-day performances in vaudeville to portraying Solomon Levy in a touring company of Abie's Irish Rose.
[3] Greenwald's Broadway credits include The Camels Are Coming (1931), Bulls, Bears and Asses (1932), Keeping Expenses Down (1932), The Great Magoo (1932), Anybody's Game (1932), Spring Song (1934), The Eldest (1935), The Postman Always Rings Twice (1936), Forbidden Melody (1936), But For the Grace of God (1937), and Hitch Your Wagon (1937).
[5] On April 1, 1938, Greenwald suffered a heart attack while portraying Joe Bonaparte in a production of Golden Boy in Santa Barbara, California.