Leo Stein, born Leo Rosenstein 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. His collaboration with Viktor Léon contributed much to Lehár's success.
A selection of his works includes Wiener Blut, Die lustige Witwe, Der Graf von Luxemburg and Die Csárdásfürstin.
Stein is buried at the Vienna Zentralfriedhof.