Joseph Legros, often also spelt Le Gros, (7 September or 8 September 1739 – 20 December 1793) was a French singer and composer of the 18th century. He is best remembered for his association with the composer Christoph Willibald Gluck and is usually regarded as the most prominent haute-contre of his generation, though his acting is reputed to have been mediocre.
Legros was born at Monampteuil, Laon. After initial training as a choirboy, when his voice broke Legros developed the voice of a haute-contre, a type of French high tenor that was typically used for the heroic male lead in French operas of the period. Legros made his début at the Paris Opéra in 1764 in a revival of Mondonville's Titon et l'Aurore and became the leading haute-contre at the Opéra, a status he held until his retirement in 1783, caused in part by his increasing obesity.
Legros began his operatic career singing the principal roles in revivals of the operas by Jean-Baptiste Lully and Jean-Philippe Rameau, and in the new works by their late followers. When in 1774, a foreign composer, Christoph Willibald Gluck, was for the first time invited to work for the Académie Royale de Musique, Legros had to confront the new composer's ground-breaking performing style. Although the singer "had an unusually brilliant and flexible upper register, particularly from top F to B flat", Gluck did not like either his expression or his acting ability, but he was obligated to entrust the company's principal tenor with the amatory leads in the operas he was going to produce. Accordingly, in 1774 Legros was charged with the roles of Achilles in Iphigénie en Aulide and, more important, Orphée in the new French version of Orfeo ed Euridice. In revising the latter opera, Gluck adapted for high tenor the male title role, originally intended for the alto castrato Gaetano Guadagni.