Jean-Philippe Rameau (/rɑːˈmoʊ/; French: [ʒɑ̃filip ʁamo]; (1683-09-25)25 September 1683 – (1764-09-12)12 September 1764) was a French Baroque composer and music theorist. Regarded as one of the most important French composers and music theorists of the 18th century, he replaced Jean-Baptiste Lully as the dominant composer of French opera and is also considered the leading French composer of his time for the harpsichord, alongside François Couperin.

Little is known about Rameau's early years. It was not until the 1720s that he won fame as a major theorist of music with his Treatise on Harmony (1722) and also in the following years as a composer of masterpieces for the harpsichord, which circulated throughout Europe. He was almost 50 before he embarked on the operatic career on which his reputation chiefly rests today. His debut, Hippolyte et Aricie (1733), caused a great stir and was fiercely attacked by the supporters of Lully's style of music for its revolutionary use of harmony.

Nevertheless, Rameau's pre-eminence in the field of French opera was soon acknowledged, and he was later attacked as an "establishment" composer by those who favoured Italian opera during the controversy known as the Querelle des Bouffons in the 1750s. Rameau's music had gone out of fashion by the end of the 18th century, and it was not until the 20th that serious efforts were made to revive it. Today, he enjoys renewed appreciation with performances and recordings of his music ever more frequent.

The details of Rameau's life are generally obscure, especially concerning his first forty years, before he moved to Paris for good. He was a secretive man, and neither his wife nor his four children knew anything of his early life, which explains the scarcity of biographical information available.

Rameau's early years are particularly obscure. He was born on 25 September 1683 in Dijon, and baptised the same day. His father, Jean, worked as an organist in several churches around Dijon, and his mother, Claudine Demartinécourt, was the daughter of a notary. The couple had eleven children, five girls and six boys, of whom Jean-Philippe was the seventh.

Rameau was taught music before he could read or write. He was educated at the Jesuit college at Godrans in Dijon, but he was not a good pupil and disrupted classes with his singing, later claiming that his passion for opera had begun at the age of twelve. Initially intended for the law, Rameau decided he wanted to be a musician, and his father sent him to Italy, where he stayed for a short while in Milan. On his return, he worked as a violinist in travelling companies, and then as an organist in provincial cathedrals, before moving to Paris for the first time. There, in 1706, he published his earliest-known compositions: the harpsichord works that make up his first book of Pièces de Clavecin, which show the influence of his friend Louis Marchand.

In 1709, he moved back to Dijon to take over his father's job as organist in the main church. The contract was for six years, but Rameau left before then and took up similar posts in Lyon and Clermont-Ferrand. During that period, he composed motets for church performance as well as secular cantatas.

In 1722, he returned to Paris for good, and there he published his most important work of music theory, Traité de l'harmonie (Treatise on Harmony). That soon won him a great reputation, and it was followed in 1726 by his Nouveau système de musique théorique. In 1724 and 1729 (or 1730), he also published two more collections of harpsichord pieces.