The Orsini family is an Italian noble family; it was one of the most influential princely families in medieval Italy and renaissance Rome. Members of the Orsini include popes Celestine III (1191–1198), Nicholas III (1277–1280), and Benedict XIII (1724–1730), 34 cardinals and numerous condottieri and other significant political and religious figures.
According to their family legend, the Orsini are descended from the Julio-Claudian family of ancient Rome. This is fanciful, as is the alleged connection to the German families of Anhalt, Baden and Bohemian Rosenberg sporting the same name. The Orsini also carried on a political feud with the Colonna family for centuries in Rome, until it was stopped by Papal Bull in 1511; in 1571 the Chiefs of both families married the nieces of Pope Sixtus V.