Pope St. Pius V (17 January 1504 – 1 May 1572), born Antonio Ghislieri (from 1518 called Michele Ghislieri, O.P.), was pope from 1566 to 1572 and is a saint of the Roman Catholic Church. He is chiefly notable for his role in the Council of Trent, the Counter-Reformation, and the standardisation of the liturgy.