Adrian Willaert (c.1490 – 7 December 1562) was a Flemish composer of the Renaissance and founder of the Venetian School.
He was one of the most representative members of the generation of northern composers who moved to Italy and transplanted the polyphonic Franco-Flemish style there.
He was probably born at Bruges, although a secondary source has suggested Roeselare. According to his student, the renowned late 16th century music theorist Gioseffo Zarlino, Willaert went to Paris first to study law, but instead decided to study music. In Paris he met Jean Mouton, the principal composer of the French royal chapel and stylistic compatriot of Josquin des Prez, and studied with him.
Sometime around 1515 Willaert first went to Rome. An anecdote survives that indicates the musical ability of the young composer: Willaert was surprised to discover the choir of the papal chapel singing one of his own compositions, most likely the six-part motet Verbum bonum et suave, and even more surprised to learn that they thought it had been written by the much more famous composer Josquin. When he informed the singers of their error – that he was in fact the composer – they refused to sing it again. Indeed Willaert's early style is very similar to that of Josquin, with smooth polyphony, balanced voices and frequent use of imitation.
In July 1515, Willaert entered the service of Cardinal Ippolito I d'Este of Ferrara. Ippolito was a traveler, and Willaert likely accompanied him to various places, including Hungary, where he likely resided from 1517 to 1519. When Ippolito died in 1520, Willaert entered the service of Duke Alfonso of Ferrara. In 1522 Willaert had a post at the court chapel of Duke Alfonso; he remained there until 1525, at which time records show he was in the employ of Ippolito II d'Este in Milan.
Willaert's most significant appointment, and one of the most significant in the musical history of the Renaissance, was his selection as maestro di cappella of St. Mark's at Venice. Music had languished there under his predecessor, Pietro de Fossis, but that was shortly to change. The Venetian Doge Andrea Gritti had a rather large hand in Willaert's appointment to the position of maestro di cappella at St. Mark's.
From his appointment in 1527 until his death in 1562, he retained the post at St. Mark's. Composers came from all over Europe to study with him, and his standards were high both for singing and composition. During his previous employment with the dukes of Ferrara, he had acquired numerous contacts and influential friends elsewhere in Europe, including the Sforza family in Milan; doubtless this assisted in the spread of his reputation, and the consequent importation of musicians from foreign countries into northern Italy. In Ferrarese court documents, Willaert is referred to as "Adriano Cantore". In addition to his output of sacred music as the director of St. Mark's, he wrote numerous madrigals, a secular form; he is considered a Flemish madrigal composer of the first rank.