Anton (or Antonio) Diabelli was born on 5 September 1781 in Mattsee, then part of the Archbishopric of Salzburg, and died on 8 April 1858 in Vienna. He sang as a boy in the choir at Salzburg Cathedral, reportedly taking lessons with Michael Haydn, and trained for the priesthood before Bavaria’s monastery closures ended that path in 1803. He then moved to Vienna, where he taught piano and guitar, worked as a proofreader for a music publisher, and in 1817 started his own music publishing business, later forming the influential firm of Cappi & Diabelli.

Diabelli was best known in his lifetime as a publisher who made popular music accessible to amateur performers, but he is remembered today chiefly as the composer of the simple waltz theme on which Ludwig van Beethoven wrote his monumental set of thirty-three Diabelli Variations. His own guitar sonatas remain part of the early Romantic guitar repertoire.

Sources:

• https://en.wikipedia.org/wiki/Anton_Diabelli