Louis Riel is an opera in three acts by the Canadian composer Harry Somers.

This full length opera was written for the 1967 Canadian centennial. It concerns the controversial Métis leader Louis Riel, who was executed in 1885, and is one of Somers' biggest pieces.

It is arguably the most famous Canadian opera. Somers set the music to an English and French libretto by Mavor Moore and Jacques Languirand. The opera was commissioned by the Floyd S. Chalmers Foundation and produced by the Canadian Opera Company with financial assistance from the Canadian Centennial Commission, the Canada Council, and the Province of Ontario Council for the Arts (Ontario Arts Council).

Louis Riel had its first performances at the O'Keefe Centre in Toronto 23 and 28 September and 11 October 1967 and at the Salle Wilfrid-Pelletier, Place des Arts, in Montreal 19 and 21 October 1967. Victor Feldbrill conducted, Leon Major directed, and Murray Laufer and Marie Day designed the sets and costumes. The original cast included Bernard Turgeon as Riel, Cornelis Opthof as Sir John A. Macdonald, Joseph Rouleau as Monseigneur Taché, Patricia Rideout as Riel's mother, Mary Morrison as his sister, Roxolana Roslak as his wife, Howell Glynne as William McDougall, and Ermanno Mauro as Baptiste Lépine.

The libretto depicts the post-Confederation political events bounded by the Indian and Métis uprisings of 1869–70 (Red River Rebellion) and 1884–5 (North-West Rebellion) and the personal tragedy of the leader of the uprisings, the Manitoba schoolteacher and Métis hero Louis Riel. After the premiere, Kenneth Winters described the opera in the Toronto Telegram (25 September 1967) as a 'pastiche ... big, efficient, exciting, heterogeneous ... It had no ring of eternity but it was a vigorous harnessing of current and choice; a brash, smart, cool hand on the pulse of a number of fashions, social, dramatic and musical.' The production was repeated in 1968 in Toronto—six performances with the assistance of the Chalmers Foundation—and was adapted by Franz Kraemer in 1969 for CBC TV.