Alceste, Wq. 37 (the later French version is Wq. 44), is an opera by Christoph Willibald Gluck from 1767. The libretto (in Italian) was written by Ranieri de' Calzabigi and based on the play Alcestis by Euripides. The premiere took place on 26 December 1767 at the Burgtheater in Vienna.

The second of Gluck's so-called "reform operas" (after Orfeo ed Euridice), it was first performed at the Burgtheater in Vienna on 26 December 1767. A heavily revised version with a French libretto by Leblanc du Roullet premiered in Paris on 23 April 1776 in the second Salle du Palais-Royal. The opera is usually given in the revised version, although this is sometimes translated into Italian. Both versions are in three acts.

Revised for presentation in Paris, Alceste became an essentially new work, the translation from Italian to French necessitating several changes in the musical declamation of text, with certain scenes significantly reorganized with new or altered music. Some of the changes were made upon the advice of Jean-Jacques Rousseau, one of Gluck's greatest French admirers. The bulk of the libretto adaptation, however, was made by French aristocrat Le Blanc du Roullet, with improvements by the composer.

Gluck fought several efforts to make the new version of Alceste conform to French tastes, resisting pressure to end the opera with an extended ballet. The new libretto does, however, introduce several subsidiary characters for dramatic variety, and, following the example of Euripides, on whose work the libretto is loosely based, even calls in Hercules in the final act.

In Don Giovanni, written in 1787, twenty years after Alceste and the year Gluck died, Mozart used exactly the same chord progression for the Commendatore speaking to Don Giovanni in the garden scene that Gluck used for the line of the High Priest when saying that Alceste will die if no one takes her place. Hector Berlioz notes how this section of Don Giovanni is "heavily in-inspired or rather plagiarized". Berlioz further discusses the authenticity of some of the arias. For example, when Gluck went to Vienna, an aria was added to act 3. Berlioz comes to the conclusion that Gluck was under so much pressure that he let it happen. Also, Berlioz notes corrections added by Gluck during rehearsals, and misunderstandings in the score, due to what Berlioz calls Gluck's "happy-go-lucky" style of writing.

Maria Callas starred as Alceste in a production at La Scala in 1954 which was recorded. It was her first collaboration in a stage performance with director Luchino Visconti.

The Metropolitan Opera has presented Alceste in three different seasons, with four sopranos starring in a total of eighteen performances. The Met premiere of the opera, on 24 January 1941, featured Marjorie Lawrence. There were four more performances that season, two starring Lawrence and two starring Rose Bampton. In the 1951/52 season, Wagnerian soprano Kirsten Flagstad sang Alceste in five performances, including her farewell performance with the company on 1 April 1952. On 6 December 1960, Eileen Farrell made her Metropolitan Opera debut as Alceste. She sang the role a total of eight times that season. Her final performance of the role, on 11 February 1961, marks the last time to date that the opera has been performed at the Met.

The Lyric Opera of Chicago opened its 1990 season with a performance of Alceste starring Jessye Norman, while Catherine Naglestad appeared in ten performances of Alceste with the Stuttgart State Opera between January and March 2006. It was given by The Santa Fe Opera as part of its summer festival season in August 2009 with Christine Brewer in the title role.

The first UK performance took place at the King's Theatre, London in 1795. More recent productions have included those in Scotland at Ledlanet in 1972 and by Scottish Opera in 1974.