Bernardo III Clesio (11 March 1484 – 30 July 1539) was an Austrian cardinal, bishop, prince, diplomat, humanist and botanist.
Born in Cles, in that period part of the County of Tyrol, today Trentino, he graduated from the University of Bologna, and later became Prince-bishop of Trento (1514–1539), bishop of Brixen (1539), cardinal, and chancellor for the Holy Roman Emperor Ferdinand I.
He was a fundamental contributor to the organization of the Council of Trent, bringing the Council to his hometown of Trento and greatly embellishing and expanding the city in the process. He commissioned the rebuilding of the Church of Santa Maria Maggiore, Trento, enlarged the Castello del Buonconsiglio and called Renaissance artists such as Dosso Dossi and Romanino to decorated the new sections.