Antonie Brentano, born Johanna Antonie Josefa Edle von Birkenstock and known as Toni, was an Austrian philanthropist, art collector, arts patron, and close friend of Beethoven, being the dedicatee of his "Diabelli" variations.

The 33 Variations on a waltz by Anton Diabelli, Op. 120, commonly known as the Diabelli Variations, is a set of variations for the piano written between 1819 and 1823 by Ludwig van Beethoven on a waltz composed by Anton Diabelli. It forms the first part of Diabelli's publication Vaterländischer Künstlerverein, the second part consisting of 50 variations by 50 other composers. It is often considered to be one of the greatest sets of variations for keyboard along with Bach's Goldberg Variations.