Giovanni Simeoni (July 12, 1816 – January 14, 1892) was an Italian prelate of the Catholic Church who was appointed a cardinal in 1875 and served as Prefect of the Sacred Congregation for Propagation of the Faith from 1878 until his death in 1892.

Simeoni received his episcopal consecration on the following April 4 from Cardinal Alessandro Franchi, with Archbishops Edward Henry Howard and Pietro Villanova Castellacci serving as co-consecrators, in the chapel of the Pontifical Urban Athenaeum of Propaganda Fide.

The Cardinal then participated in the conclave of 1878, which resulted in the election of Pope Leo XIII, who confirmed him as Prefect of the Apostolic Palace and Administrator of the Patrimony of the Holy See.

Simeoni was named Prefect of the Sacred Congregation for the Propagation of the Faith, also known as the "Red Pope", on March 5, 1878, and president of the missionary seminaries of Rome on January 1, 1885.

During his tenure as the head of the Catholic Church's global missionary network, Cardinal Simeoni became very important to the history of African-American Roman Catholicism.

Cardinal Simeoni famously quipped, while issuing the orders in a document that still survives in the Vatican archives, "America has been called the most enlightened nation.