Giovanni (Gian) Giacomo Teodoro Trivulzio (1597 – 3 August 1656) was an Italian Cardinal who held several high functions in service of the Spanish Crown.

Trivulzio was born and died in Milan, Duchy of Milan. He was the son of Carlo Emanuele Teodoro Trivulzio, Count of Melzo, who died when Gian Giacomo was still very young, and Catherina Gonzaga. His sister was Ippolita Trivulzio. In Austria, a 17th century bronze coin depicting the Cardinal's portrait still exists.^[1]

According to Sebastián Francisco de Medrano's miscellany Favores de las Musas, dedicated to Trivulzio himself in 1631, the Cardinal's full title is as follows: The Most Eminent and Excellent Lord His Excellency Theodoro Trivulzio Diacono, Cardinal of the Holy Roman Church of the Title of San Crisogono, Legate a latere of the Holy Apostolic See and of our Most Blessed Lord Pope Urban VIII, in the Province of La Marca of Ancona, Vicar General in spiritual, civil, and temporal matters of the Holy Roman Empire, Prince of Misocco and the Misolcino, Count of Melcio and Gorgonzola, Lord of Cotoño and Venzaguelo.^[2]

In 1615 he married Giovanna Maria Grimaldi, daughter of Hercule, Lord of Monaco, and wife Maria Landi.
They had two daughters and one son:

• Ottavia (1618), married Tolomeo II Gallio (1618 - Milan, 28 January 1687), 4th Duke of Alvito, great-grandson of Ottavio Farnese, Duke of Parma, and had issue
• Caterina,
• Ercole Teodoro, Knight of the Order of the Golden Fleece.

When his wife died in 1620, Gian Giacomo entered the Church. On 19 November 1629, he became a cardinal.^[3] In 1642 he became Viceroy of Aragon, and Grandee of Spain.

He participated in the Papal conclave, 1644, which finally chose Pope Innocent X, and in the Papal conclave, 1655, which elected Pope Alexander VII, and where Gian Giacomo as protodeacon gave the Habemus Papam announcement.

Between 1647 and 1649 he was Viceroy of Sicily and between 1649 and 1651 Viceroy of Sardinia. In April 1656 he became interim Governor of the Duchy of Milan, a post he held until his death. He died in Milan on 3 August 1656 and was buried in the family vault in the Santo Stefano church.

• Gridario dell'eminentissimo e reverendissimo signore il signor Theodoro cardinale principe Trivulzio (in Italian). Milano: Marco Antonio Pandolfo Malatesta. 1656.

• The Cardinals of the Holy Roman Church, Biographical Dictionary, Pope Urban VIII (1623-1644), Consistory of November 19, 1629 (V)