Marcello Cervini was born on May 6, 1501 at Montepulciano to the noble Cervini family. A learned humanist and papal secretary, Cervini served as papal legate at the opening of the Council of Trent (1545–1547) — one of the three papal legates at the Council's first session.
Elected Pope on April 9, 1555, taking the name Marcellus II (retaining his baptismal name — the last pope to do so until Pope Francis 2013–), Marcellus II intended a systematic reform of the papal court and the Catholic hierarchy.
But his reforming pontificate lasted only 22 days — he died at Rome on May 1, 1555 of a stroke, without being able to implement his reforming vision.
Marcellus II's most enduring legacy is the Missa Papae Marcelli ('Mass for Pope Marcellus') — composed by Giovanni Pierluigi da Palestrina (c. 1525–1594, father of the Catholic polyphonic sacred music tradition) around 1562, in honor of Marcellus II. The Missa Papae Marcelli — one of the most famous Renaissance polyphonic Masses — became the classical example of the Tridentine sacred music tradition, establishing the specifically Tridentine principle of intelligible-liturgical polyphonic composition.