Pope Paul III (Latin: Paulus III; Italian: Paolo III; 29 February 1468 – 10 November 1549), born Alessandro Farnese, was head of the Catholic Church and ruler of the Papal States from 13 October 1534 to his death in 1549.

He came to the papal throne in an era following the sack of Rome in 1527 and rife with uncertainties in the Catholic Church following the Protestant Reformation. His pontificate initiated the Counter-Reformation with the Council of Trent in 1545, as well as the Wars of religion with Emperor Charles V's military campaigns against the Protestants in Germany. He recognized new Catholic religious orders and societies such as the Jesuits, the Barnabites, and the Congregation of the Oratory. His efforts were distracted by nepotism to advance the power and fortunes of his family, including his illegitimate son Pier Luigi Farnese.

Paul III was a significant patron of artists including Michelangelo, and it is to him that Nicolaus Copernicus dedicated his heliocentric treatise.