Christoph Willibald (von) Gluck (2 July 1714 - 15 November 1787) was a German composer, one of the most important opera composers of the Classical music era, particularly remembered for Orfeo ed Euridice. Gluck's operatic reforms, eliminating all that was undramatic, were a turning point in the history of the medium.

Gluck's musical legacy was around 35 complete operas, together with numerous ballets and instrumental works. His reforms influenced Wolfgang Amadeus Mozart, particularly his opera Idomeneo (1781). Gluck left behind a flourishing school of disciples in Paris, who would dominate the French stage throughout the Revolutionary and Napoleonic period. As well as Antonio Salieri, they included Antonio Sacchini, Luigi Cherubini, Étienne Méhul and Gaspare Spontini. Gluck's greatest French admirer would be Hector Berlioz, whose epic Les Troyens may be seen as the culmination of the Gluckian tradition.

Though Gluck wrote no operas in German, his example influenced the German school of opera, particularly Carl Maria von Weber and Richard Wagner, whose concept of music drama was not so far removed from Gluck's own.