| Honorific-Prefix: | Most Reverend |
| Zacharias Ferrari | |
| Bishop of Guardialfiera | |
| Church: | Catholic Church |
| Diocese: | Diocese of Guardialfiera |
| Term: | 1519 and 1521–1524 |
| Predecessor: | Valentinus de Valentiuis |
| Successor: | Girolamo Vascheri |
| Death Date: | 1524 |
| Previous Post: | Titular Bishop of Sebaste in Cilicia (1518–1519) |
Zacharias Ferreri or Ferrari (1479–1524) was an Italian monk and papal legate, Latin poet and ecclesiastical writer.
Ferreri was born in Vicenza to a noble family. As a student in Padua, he became a Benedictine monk at the Abbey of Monte Cassino. However, at the age of 25 he left the monastery and moved to Rome. He finished his education receiving master's degrees in law and theology. He served Pope Julius II but soon joined ranks of his opponents and attended the Conciliabulum of Pisa in 1511. For these activities he was excommunicated in 1513. He made peace with the new Pope Leo X and was tasked with preparing a new, shorter and more convenient, edition of the breviary. In 1518 he became titular Bishop of Sebaste in Cilicia and was nominated to become Bishop of Guardialfiera.[1] [2] He renounced the nomination two months later, but kept the title and rights.[3]
In 1520–21 he was sent as a papal legate to the Kingdom of Poland and Grand Duchy of Lithuania. In Poland he mediated a truce in the Polish–Teutonic War (1519–21) and campaigned against the spread of Lutheranism. In Lithuania he investigated evidence for the canonization of Saint Casimir. His planned journey to the Grand Duchy of Moscow was cancelled. In 1521, he returned to Rome and continued working on the breviary. After the death of Pope Leo X on 1 December 1521, he claimed his rights as Bishop of Guardialfiera then occupied by Valentinus de Valentiuis. His breviary was published after his death in 1524.