The Pazzi were a powerful family in the Republic of Florence. Their main trade during the fifteenth century was banking. In the aftermath of the Pazzi conspiracy in 1478, members of the family were banished from Florence and their property was confiscated; the family name and coat-of-arms were permanently suppressed by order of the Signoria.

The traditional story is that the family was founded by Pazzo di Ranieri, first man over the walls during the Siege of Jerusalem of 1099, during the First Crusade, who returned to Florence with flints supposedly from the Holy Sepulchre, which were kept at Santi Apostoli and used on Holy Saturday to re-kindle fire in the city.^{[1][2]: 131} The historical basis of this legend has been in question since the work of Luigi Passerini Orsini de' Rilli [it] in the mid-nineteenth century.^[1]

The first apparently historical figure in the family is the Jacopo de' Pazzi il Vecchio [it] who was a captain of the Florentine (Guelph) cavalry at the battle of Montaperti on 4 September 1260, and whose hand was treacherously severed by Bocca degli Abati [it], causing the standard to fall.^[3] His son Pazzino di Jacopo de' Pazzi [it] was a Black Guelph and a follower of Charles de Valois.^[3]

Andrea di Guglielmo de' Pazzi (1372–1445) was a banker and merchant. In 1429 he commissioned construction of the Pazzi Chapel in the Franciscan church of Santa Croce in Florence.^[4] His son Jacopo de' Pazzi became head of the family in 1464.^[2]: 131

Guglielmo di Antonio de' Pazzi married Bianca de' Medici, sister of Lorenzo de' Medici, in 1460;^[3] Cosimo de' Pazzi [it], the sixth of their sixteen children, became archbishop of Florence in 1508.^[5]

Francesco de' Pazzi was one of the instigators of the Pazzi conspiracy in 1477–78. He, Jacopo de' Pazzi and Jacopo's brother Renato de' Pazzi were executed after the plot failed.^[2]: 141

Raffaele de' Pazzi [it] was a condottiere; he died at the Battle of Ravenna in 1512.^[6]

Maria Maddalena de' Pazzi (1566–1607) was a Carmelite nun and mystic;^[7]: 218 she was canonised in 1669.^[8]: 149

The Pazzi Chapel in the Franciscan church of Santa Croce in Florence was commissioned by Andrea di Guglielmo de' Pazzi in 1429.^[4] It was designed by Filippo Brunelleschi.^{[10][lower-alpha 1]} Construction began in 1442 in a cloister of the church, and continued after the death of the patron in 1445 and the architect in 1446; work was interrupted by the Pazzi plot and the chapel was never completed.^{[11]: 107 [4]}

Palazzo Pazzi or Palazzo Pazzi-Quaratesi was the main seat of the family in the "Canto dei Pazzi", at the intersection of Borgo degli Albizi [it] and via del Proconsolo [it]. It was commissioned by Jacopo de' Pazzi, and built circa 1462–1472 to designs by Giuliano da Maiano. Above its traditionally rusticated ground floor of yellow-ochre sandstone, it had a then-novel stuccoed first and second floor, with delicate designs in the windows influenced by Brunelleschi. The central court is surrounded on three sides by round-headed arcading, with circular bosses in the spandrels.^{[citation needed]}

Palazzo Pazzi Ammannati [it] (or Palazzo Pazzi dell'Accademia Colombaria) is a smaller palace in the Borgo degli Albizi, between Palazzo Ramirez de Montalvo and the Palazzo Nonfinito. It houses a section of the Museum of Natural History of Florence, and hosts temporary exhibitions. The façade is attributed to Bartolomeo Ammannati.^{[citation needed]}