The Odescalchi family were entrepreneurs with the minor nobility of Como.They trace their family line to Giorgio Odescalchi of Como, around 1290.
Pietro Giorgio Odescalchi was Bishop of Alessandria (1598-1610) and then Bishop of Vigevano (1610–1620).
Benedetto Odescalchi reigned as Pope Innocent XI from 1676 until 1689. As the last male heir to the family, their fortune passed to the descendants of his sister, Lucrezia Odescalchi, who had married Alessandro Erba in 1621. The Erba family is allegedly descended from Enrico Erba, an Imperial vicar in Milan, around 1165. The title of Prince of the Holy Roman Empire was conferred on their grandson Baldassare Erba-Odescalchi in 1714, along with the title, Duke of Syrmia in the Kingdom of Hungary and the qualification of Serene Highness.
The Pope’s grand-nephew Cardinal Benedetto Erba Odescalchi held a doctorate in Civil and Canon Law (Pavia, 1700), and was Papal Nuncio in Poland from 1712 to 1714. He was named Archbishop of Milan in 1712 (resigning in 1736 after a stroke), and was created a cardinal in January 1714. He died in Milan on 13 December 1740.
Antonio Maria Erba-Odescalchi, Pope Innocent’s great-grandnephew and Cardinal Benedetto Erba-Odescalchi’s nephew, was a Doctor in Civil and Canon Law (Milan 1733), which allowed him to pursue a career in the Papal Court in Rome as a church lawyer. He became a Protonotary Apostolic in 1737 and a Referendary (Judge) of the Two Tribunals of Justice and Grace in 1739. He was named a cardinal in 1759 and given the office of Vicar-General of the Pope for the City of Rome. He died in 1762.
Carlo Odescalchi, S.J., was the son of Prince Baldassare Erba-Odescalchi, and Valeria Caterina Giustiniani. His family was in exile in Hungary during his youth, having fled the French forces of First Consul Bonaparte. He obtained a Doctorate in Civil and Canon Law. Pope Pius VII sent him on several minor diplomatic missions to Hungary. He became Auditor (Judge) of the Sacred Roman Rota in 1815, and joined the restored Society of Jesus in 1818. He was promoted Auditor of His Holiness and Canon of the Vatican Basilica. On 10 March 1823 Odescalchi was created a cardinal and named Archbishop of Ferrara; he resigned the diocese in 1826 to pursue a higher career in the Papal Curia as Prefect of the Congregation of Bishops and Regulars. He was named Bishop of Sabina in 1833; he resigned in 1838 to return to the Jesuits. He died in Modena in 1841.