| Type: | Bishop |
| Honorific-Prefix: | Most Reverend |
| Mario Cossa | |
| Bishop of Montalcino | |
| Church: | Catholic Church |
| Diocese: | Diocese of Montalcino |
| Term: | 1607–1618 |
| Predecessor: | Camillo Borghese (archbishop) |
| Successor: | Ippolito Borghese (bishop) |
| Consecration: | 29 Apr 1607 |
| Consecrated By: | Roberto Francesco Romolo Bellarmino |
| Birth Place: | Siena, Italy |
| Death Date: | 1618 |
Mario Cossa (died 1618) was a Roman Catholic prelate who served as Bishop of Montalcino (1607–1618).[1]
Mario Cossa was born in Siena, Italy.[2] On 2 Apr 1607, he was appointed during the papacy of Pope Paul V as Bishop of Montalcino.On 29 Apr 1607, he was consecrated bishop by Roberto Francesco Romolo Bellarmino, Cardinal-Priest of San Matteo in Merulana, with Antonio Caetani (iuniore), Archbishop of Capua, and Metello Bichi, Bishop Emeritus of Sovana, serving as co-consecrators. He served as Bishop of Montalcino until his death in 1618.