Alcina (HWV 34) is an opera seria by George Frideric Handel. Handel used the libretto of L'isola di Alcina, an opera that was set in 1728 in Rome by Riccardo Broschi, which he acquired the year after, during his travels in Italy. The plot was originally taken from – but partly altered for better conformity – Ludovico Ariosto's Orlando furioso (like those of the Handel operas Orlando and Ariodante), an epic poem set in the time of Charlemagne's wars against Islam. The opera contains several musical sequences with opportunity for dance: these were composed for dancer Marie Sallé.

Alcina was composed for Handel's first season at the Covent Garden Theatre, London. It premiered on April 16, 1735. Like the composer's other works in the opera seria genre, it fell into obscurity; after a revival in Brunswick in 1738 it was not performed again until a production in Leipzig in 1928.

The Australian soprano Joan Sutherland sang the role in a production by Franco Zeffirelli in which she made her debut at La Fenice in February 1960 and at the Dallas Opera in November of that year. She performed in the same production at the Royal Opera House, Covent Garden, in 1962. It was performed at Ledlanet, Scotland, in 1969. A major production was that of Robert Carsen, staged originally for the Opera de Paris in 1999 and repeated at the Lyric Opera of Chicago, which featured Renée Fleming in the title role.