Girolamo Rusticucci (1537 – 14 June 1603) was an Italian Roman Catholic cardinal and bishop. He was personal secretary to Cardinal Michele Ghislieri, later Pope Pius V, who made Rusticucci a cardinal. He occupied numerous important positions, including papal legate to France and Spain, Camerlengo (treasurer) and Vice-Dean of the College of Cardinals, and Vicar General of Rome. He built a palace near Saint Peter's Square in Rome, located on a new piazza that was named after the cardinal.