Franz Lehár (born 30 April 1870; died 24 October 1948) was an Austrian composer of Hungarian descent. He was the leading composer of operettas in the 20th century. He is still one of the most popular composers of light music.

Lehár was born in Komáron in the Austro-Hungarian Empire. Today the town is called Komárno and it is in Slovakia. He was the eldest son of a bandmaster in the Austro-Hungarian army. He studied violin and composition at the Prague Conservatory. Antonín Dvořák told him he should be a composer. After graduation in 1899, he joined his father's band in Vienna, as assistant bandmaster. In 1902 he became conductor at the historic Vienna Theater an der Wien, where his first opera Wiener Frauen was performed in November of that year.

He is most famous for his operettas. The best known one is The Merry Widow (in German: Die lustige Witwe) which is probably the most popular of all operettas. He also wrote sonatas, symphonic poems, marches, and a number of waltzes, some of which come from his famous operettas. Some of the songs from his operettas have become very well-known, especially "Vilja" from The Merry Widow and "You Are My Heart's Delight" ("Dein ist mein ganzes Herz") from The Land of Smiles.

The tenor Richard Tauber sang in many of his operettas. Six of them had parts especially written for him.

Lehár died in 1948 in Bad Ischl, near Salzburg where he was also buried. His villa in Bad Ischl is now a museum in his memory.