Josquin Lebloitte dit des Prez (c. 1450–1455 – 27 August 1521) was a composer of Renaissance music, who is variously described as French or Franco-Flemish. Considered one of the greatest composers of the Renaissance, he was a central figure of the Franco-Flemish School and had a profound influence on the music of 16th-century Europe. Building on the work of his predecessors like Johannes Ockeghem, he developed a complex style of expressive—and often imitative—movement between independent voices (polyphony) which informs much of his work. He further emphasized the relationship between text and music, and departed from the early Renaissance tendency towards lengthy melismatic lines on a single syllable, preferring to use shorter, repeated motifs between voices. Josquin was a singer, and his compositions are mainly vocal. They include masses, motets and secular chansons.

Josquin's biography has been continually revised by modern scholarship. He was born somewhere in what is now northeastern France or Belgium and by 1477 he was in the choir of René of Anjou, later probably serving under Louis XI of France. In the 1480s Josquin traveled Italy with the Cardinal Ascanio Sforza, may have worked in Vienna for the Hungarian king Matthias Corvinus, and wrote the motet Ave Maria ... Virgo serena, and the popular chansons Adieu mes amours and Que vous ma dame. He served Pope Innocent VIII and Pope Alexander VI in Rome, Louis XII in France, and Ercole I d'Este in Ferrara. Many of his works were printed and published by Ottaviano Petrucci, including the Missa Hercules Dux Ferrariae. In his final years in Condé, Josquin produced some of his most admired works, including the motets Benedicta es, Inviolata, Pater noster–Ave Maria and Praeter rerum seriem, and the chansons Nimphes, nappés and Plus nulz regretz.

Influential both during and after his lifetime, Josquin has been described as the first Western composer to retain posthumous fame. His music was widely performed and imitated in 16th-century Europe, and was highly praised by Martin Luther and the music theorists Heinrich Glarean and Gioseffo Zarlino. In the Baroque era, Josquin's reputation became overshadowed by the Italian composer Giovanni Pierluigi da Palestrina. During the 19th- and 20th-century early music revival, publications by August Wilhelm Ambros, Albert Smijers, Helmuth Osthoff, and Edward Lowinsky culminated in a successful academic conference in 1971. This caused a reevaluation of Josquin as a central figure in Renaissance music, although some scholars have questioned whether he has been unrealistically elevated over his contemporaries. Josquin continues to draw interest in the 21st century and his music is frequently recorded and the subject of continuing scholarship. He was celebrated worldwide on the 500th anniversary of his death in 2021.

Josquin's full name, Josquin Lebloitte dit des Prez, became known in the late 20th century. A pair of 1483 documents found in Condé-sur-l'Escaut identify the composer as the nephew of Gille Lebloitte dit des Prez and the son of Gossard Lebloitte dit des Prez. His first name Josquin is a diminutive form of Josse, the French form of the name of Judoc, a Breton saint of the 7th century. Josquin was a common name in Flanders and Northern France in the 15th and 16th centuries. Other documents indicate that the surname des Prez had been used by the family for at least two generations, perhaps to distinguish them from other branches of the Lebloitte family. At the time, the name Lebloitte was rare and the reason that Josquin's family took up the more common surname des Prez as their dit name remains uncertain.

His name has many spellings in contemporary records: his first name is spelled as Gosse, Gossequin, Jodocus, Joskin, Josquinus, Josse, Jossequin, Judocus and Juschino; and his surname is given as a Prato, de Prato, Pratensis, de Prés, Desprez, des Prés and des Près. In his motet Illibata Dei virgo nutrix, he includes an acrostic of his name, where it is spelled IOSQVIN Des PREZ. Documents from Condé, where he lived for the last years of his life, refer to him as "Maistre Josse Desprez". These include a letter written by the chapter of Notre-Dame of Condé to Margaret of Austria where he is named as "Josquin Desprez". Scholarly opinion differs on whether his surname should be written as one word (Desprez) or two (des Prez), with publications from continental Europe preferring the former and English-language publications the latter. Modern scholarship typically refers to him as Josquin.

Little is known about Josquin's early years. The specifics of his biography have been debated for centuries. The musicologist William Elders noted that "it could be called a twist of fate that neither the year, nor the place of birth of the greatest composer of the Renaissance is known". He is now thought to have been born around 1450, and at the latest 1455, making him "a close contemporary" of composers Loyset Compère and Heinrich Isaac, and slightly older than Jacob Obrecht. Josquin's father Gossart dit des Prez was a policeman in the castellany of Ath, who was accused of numerous offenses, including complaints of undue force, and disappears from the records after 1448. Nothing is known of Josquin's mother, who is absent from surviving documents, suggesting that she was either not considered Josquin's legitimate mother, or that she died soon after, or during, his birth. Around 1466, perhaps on the death of his father, Josquin was named by his uncle and aunt, Gille Lebloitte dit des Prez and Jacque Banestonne, as their heir.

Josquin was born somewhere in what is now northeastern France or Belgium. Despite his association with Condé in his later years, Josquin's own testimony indicates that he was not born there. The only firm evidence for his birthplace is a later legal document in which Josquin described being born beyond Noir Eauwe, meaning 'Black Water'. This description has puzzled scholars, and there are various theories on which body of water is being referred to. L'Eau Noire river in the Ardennes has been proposed, and there was a village named Prez there, though the musicologist David Fallows contends that the complications surrounding Josquin's name make a surname connection irrelevant, and that the river is too small and too far from Condé to be a candidate. Fallows proposes a birthplace near the converging Escaut and Haine rivers at Condé, preferring the latter since it was known for transporting coal, perhaps fitting the "Black Water" description. Other theories include a birth near Saint-Quentin, Aisne, due to his early association with the Collegiate Church of Saint-Quentin, or in the small village of Beaurevoir, which is near the Escaut, a river that may be referred to in an acrostic in his later motet Illibata Dei virgo nutrix.

There is no documentary evidence covering Josquin's education or upbringing. Fallows associates him with Goseequin de Condent, an altar boy at the collegiate church of Saint-Géry, Cambrai until mid-1466. Other scholars such as Gustave Reese relay a 17th-century account from Cardinal Richelieu's friend Claude Hémeré, suggesting that Josquin became a choirboy with his friend Jean Mouton at the Collegiate Church of Saint-Quentin; this account has been questioned. The collegiate chapel there was an important center of royal patronage and music for the area. All records from Saint-Quentin were destroyed in 1669, and Josquin may have acquired his later connections with the French royal chapel through an early association with Saint-Quentin. There is no evidence that Josquin studied with Johannes Ockeghem, as claimed by later writers such as Gioseffo Zarlino and Lodovico Zacconi. Later commentators probably only have meant that Josquin "learnt from the older composer's example". Josquin wrote a lamentation on the death of Ockeghem, Nymphes des bois, he also musically quoted Ockeghem several times, most directly in his double motet Alma Redemptoris mater/Ave regina caelorum, which shares an opening line with Ockeghem's motet Alma Redemptoris mater.