Carlo Odescalchi, (5 March 1785 – 17 August 1841) was an Italian prince and priest, Archbishop of Ferrara, cardinal of the Catholic Church and Vicar General of the Diocese of Rome.

Carlo was first educated at home by his father, but from 1798 to 1800 studied in a seminary in Hungary, where the family lived for a time in exile after fleeing from the invading armies of the French First Consul Napoleon Bonaparte.

Pius VII, following his release from France, sent Odescalchi to Olomouc in 1815 as a papal legate to Antonín Colloredo-Waldsee, and again in 1819 to bestow the cardinalatial red biretta on Archduke Rudolf of Austria.

On 10 March 1823, Pius VII appointed Odescalchi the Archbishop of Ferrara and also created him Cardinal Priest with the title of Santi Apostoli.

Appointed Grand Prior of the Sovereign Military Order of Malta in Rome, he again asked the Pope to accept his resignation, which Gregory did this time.