What is the name of Beethoven's only opera?

Beethoven’s only opera is Fidelio.

Fidelio is the sole opera by Ludwig van Beethoven, although the work went through several revisions before reaching its final form. Its plot centers on Leonore, who disguises herself as a prison guard named Fidelio to rescue her husband, Florestan, a political prisoner. The opera combines a personal story of marital devotion with themes of justice, freedom, and resistance to tyranny.

The libretto began with Joseph Sonnleithner, based on a French text by Jean-Nicolas Bouilly. Beethoven’s first version premiered in Vienna in 1805 under the title Leonore. He revised it for a second production in 1806, and a substantially refined version, now called Fidelio, premiered in 1814. The opera’s famous rescue finale celebrates Florestan’s liberation and the triumph of moral courage.

The title can cause confusion because Leonore is the central character and the opera originally carried her name. Fidelio is the name Leonore adopts while disguised. Beethoven also wrote stage works and incidental music, but none of them is another full opera, which is why Fidelio is consistently identified as his only opera.