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| Type: | Bishop |
| Honorific-Prefix: | Most Reverend |
| Leonardo Marsili | |
| Archbishop of Siena | |
| Church: | Catholic Church |
| Archdiocese: | Archdiocese of Siena |
| Term: | 1682–1713 |
| Predecessor: | Celio Piccolomini |
| Successor: | Alessandro Zondadari |
| Ordination: | 17 May 1665 |
| Consecration: | February 1682 |
| Consecrated By: | Gasparo Carpegna |
| Birth Date: | 15 May 1641 Siena, Italy |
| Birth Place: | Siena, Italy |
| Death Date: | 8 Apr 1713 (age 78) |
| Death Place: | Siena, Italy |
Leonardo Marsili (1641–1713) was a Roman Catholic prelate who served as Archbishop of Siena (1682–1713).
Leonardo Marsili was born in Siena, Italy on 15 May 1641 and ordained a priest on 17 May 1665.On 26 Jan 1682, he was appointed during the papacy of Pope Innocent XI as Archbishop of Siena.In February 1682, he was consecrated bishop in Rome by Gasparo Carpegna, Cardinal-Priest of San Silvestro in Capite.He served as Archbishop of Siena until his death on 8 Apr 1713 in Siena.
While bishop, he was the principal co-consecrator of Ulisse Giuseppe Gozzadini, Titular Archbishop of Teodosia (1700).