Sémélé is an opera by Marin Marais with a libretto by Antoine Houdar de la Motte first performed on 9 April 1709, by the Paris Opera at the Théâtre du Palais-Royal. The opera is in the form of a tragédie en musique with a prologue and five acts.

Master viol player and composer Marin Marais became director of the Paris Opera in 1705 and presented, along with the established works of Jean-Baptiste Lully, two operas of his own during his brief tenure which ended in 1709. His opera Alcyone (1706) proved a successful stage work and was revived several times during the 18th Century. His final opera Sémélé (1709) did not fare as well. Opening during The Great Frost, an extraordinarily cold European winter that afflicted France particularly hard with food shortages and violent revolts in the streets of Paris, demand for Sémélé (and other new works introduced during this period) was modest. Amid the tumult, Marais retired as Director of the Opera to return to writing viol music. Sémélé disappeared from the repertory for nearly 300 years until a modern performing score published by France's Centre de Musique Baroque de Versailles revived interest in the work. Commemorating the 350th anniversary of the composer's birth, the French period-instrument ensemble Le Concert Spirituel, under the baton of Herve Niquet, performed the opera in concert at the Festival International d'Opéra Baroque in Beaune and then in Paris in 2006. The following year, the same ensemble presented Sémélé (minus Marais' 30-minute prologue, which was cut) in a fully staged production directed by Olivier Simonnet in Montpellier. The opera was presented for the first time outside of Europe by conductor Jeffrey Thomas and American Bach Soloists in San Francisco, August 13–14, 2015.

John Eccles 1707 opera Semele is based on the same myth from Ovid's Metamorphoses, and set to a libretto by William Congreve. This libretto (in expanded form) later served as the basis for yet another opera, by George Frideric Handel (1744). Based on a libretto by de la Motte, Marais' work bears significant narrative differences from the Congreve-based operas. Handel's Semele is a well known standard repertory opera today.