Rosario DeSimone (Italian pronunciation: [roˈzaːrjo desiˈmoːne]; 11 December 1873 – 15 July 1946) was the head of an Italian American crime family during the 1920s to 1940s that was the predecessor to the Los Angeles crime family of the American Mafia.
Rosario was the father of the future California mob boss, Frank DeSimone.
After immigrating to the United States, he initially settled in New Orleans before moving to Pueblo, Colorado.
He became a close ally of Vito Di Giorgio in Los Angeles.
His second son, Frank DeSimone, became a criminal attorney and later don of the crime family, reigning from 1956 to 1967.