Leo Stein, born Leo Rosenstein (25 March 1861, Lemberg – 28 July 1921, Vienna, Austria) was a playwright and librettist of operettas in the latter part of the 19th and early 20th centuries, including works adapted for a number of Broadway productions.
Stein wrote libretti for Johann Strauss Jr, Franz Lehár, Emmerich Kálmán, and Oskar Nedbal.