Girolamo I Angeli (Latin: Hieronymus Angelus;[1][2] 1505–1591) was a joint, or rival, Grand Master of the Constantinian Order of Saint George from 1570 to 1591, together with, or against, his brother Andrea and then his nephew Pietro.
[4] In the mid-15th century, Girolamo's older brothers Andrea and Paolo were officially acknowledged as descendants of the Angelos emperors by Pope Paul III (r. 1534–1549) and founded the Sacred Military Constantinian Order of Saint George,[5][6] a chivalric order with invented Byzantine connections.
[7] Girolamo was a rival claimant to the position of Grand Master, challenging Andrea, and managed to at one point secure recognition of the papacy, given that at least one surviving papal document refers to Girolamo as the Grand Master.
Though Girolamo eventually accepted the principle of primogeniture, accepting the accession of his nephew Pietro Angeli in 1580,[8] Girolamo remains recognized as a Grand Master, concurrent with Andrea and Pietro, in modern records of the Constantinian Order.
Girolamo's at first adulterous relationship with Ursula Bini led to later issues concerning the Angeli succession, as the claims of Michele's children to the position of grand master would be challenged by Andrea.