Girolamo Savonarola (UK: , US: , Italian: [dʒiˈrɔːlamo savonaˈrɔːla]; 21 September 1452 – 23 May 1498) or Jerome Savonarola was an Italian Dominican friar from Ferrara and preacher active in Renaissance Florence. He was known for his prophecies of civic glory, the destruction of secular art and culture, and his calls for Christian renewal. He denounced clerical corruption, despotic rule, and the exploitation of the poor.

In September 1494, when Charles VIII of France invaded Italy and threatened Florence, such prophecies seemed on the verge of fulfilment. While Savonarola intervened with the French king, the Florentines expelled the ruling Medicis and, at the friar's urging, established a "popular" republic. Declaring that Florence would be the New Jerusalem, the world centre of Christianity and "richer, more powerful, more glorious than ever", he instituted an extreme puritanical campaign, enlisting the active help of Florentine youth.

In 1495 when Florence refused to join Pope Alexander VI's Holy League against the French, the Vatican summoned Savonarola to Rome. He disobeyed and further defied the pope by preaching under a ban, highlighting his campaign for reform with processions, bonfires of the vanities, and pious theatricals. In retaliation, the pope excommunicated him in May 1497, and threatened to place Florence under an interdict. A trial by fire proposed by a rival Florentine preacher in April 1498 to test Savonarola's divine mandate turned into a fiasco, and popular opinion turned against him. Savonarola and two of his supporting friars were imprisoned. On 23 May 1498, Church and civil authorities condemned, hanged, and burned the three friars in the main square of Florence.

Savonarola's devotees, the Piagnoni, kept his cause of republican freedom and religious reform alive well into the following century, although the Medici—restored to power in 1512 with the help of the papacy—eventually broke the movement. Some Protestants, including Martin Luther himself, consider Savonarola to be a vital precursor to the Reformation.