Giovanni Battista Rinuccini (15 September 1592 – 28 December 1653) was an Italian Roman Catholic archbishop in the mid-seventeenth century. He was a noted legal scholar and became chamberlain to Pope Gregory XV, who made him the Archbishop of Fermo in Italy. He is best known for his time as Papal Nuncio to Ireland during the Irish Confederate Wars (1645–49) during the Wars of the Three Kingdoms. Rinuccini became the dominant figure of the Clerical Faction of the Confederate leadership, pushing for greater concessions to the Catholic Church in any treaty of alliance with Irish Royalists.
Rinuccini was born at Rome in 1592. He was the son of a Florentine patrician, his mother, Virginia di Pier Antonio Bandini was a sister of Ottavio Bandini. Educated by the Jesuits at Rome and in courses of law at the Universities of Bologna and Perugia, in due course he was ordained a priest, having at the age of twenty-two obtained his doctor's degree from the University of Pisa. He was accepted into the Accademia della Crusca. Returning to serve his uncle at Rome, although a fever permanently damaged his health, he won distinction as an advocate in the ecclesiastical courts, was named a camariere by Pope Gregory XV and in 1625 became Archbishop of Fermo. In 1631 he carefully refused an offer to be made archbishop of Florence.