The Acciaioli, Acciaiuoli, or Acciajuoli was an important family of Florence.
Family name is also written Acciaioli, Acciainoli, or Accioly, Accioli and Acyoly in Portugal and Brazil, where there are branches of it. Descent can be traced in an unbroken line from one Gugliarello Acciaioli in the 12th century; family legend says that Gugliarello (a name possibly derived from It. guglia, needle) migrated from Brescia to Florence in 1160 because they were Guelphs and fled Barbarossa's invasion of Northern Italy. The Acciaioli founded a powerful bank in the 13th century (Compagna di Ser Leone degli Acciaioli e de' suoi consorti) which had branches from Greece to Western Europe. Bishop Angiolo Acciaioli briefly ruled Florence in the mid-14th century after the deposition of Gauthier de Brienne. Later they associated themselves to the Albizzi and then to the elder Medici in the 15th century. From about 1390 to 1460 they ruled the Duchy of Athens and kept close ties with the younger branch of the Medici through the marriage of Laudomia Acciaioli to Pierfrancesco de' Medici, from which the later Grand Dukes of Tuscany are descended, as well as several royal houses.
Simone di Zanobi Acciaioli migrated before 1512 to the island of Madeira where he represented the family's commercial interests. The Portuguese and Brazilian Accioly or Accioli family is descended from him.
In the 14th and 15th centuries the Acciaioli family conquered and ruled the Duchy of Athens.
 Family members
- Angelo Acciaioli I (1298–1357), bishop
- Angelo Acciaioli II (1349–1408), cardinal
- Angelo Acciaioli di Cassano (died 1467), diplomat
- Antonio I Acciaioli (died 1435), Duke of Athens
- Antonio II Acciaioli (died 1445), Duke of Athens
- Donato Acciaioli (1428–1478), scholar
- Francesco I Acciaioli (floruit 1451–1453), Duke of Athens
- Francesco II Acciaioli (died 1460), last Duke of Athens
- Giovanni Acciaioli (floruit 1422), archbishop of Thebes
- Nerio I Acciaioli (died 1394), first Acciaioli Duke of Athens
- Nerio II Acciaioli (died 1451), twice Duke of Athens
- Niccolò Acciaioli (1310–1365), soldier and statesman
- Zanobi Acciaioli (1461-1519), Dominican monk and scholar
 Other sources
- Litta, Pompeo (1830-1845). "Acciaioli di Firenze". Famiglie Celebri Italiane.
- Ugurgieri della Berardenga, Curzio (1962). Gli Acciaioli di Firenze nella luce de' loro tempi.
- Albuquerque et al., Cassia (2011). Acciaiolis no Brasil (in Portuguese).