Rudolph Johann Joseph Rainier, Archduke of Austria, Prince Royal of Hungary and Bohemia, Cardinal-Archbishop of Olomouc (8 January 1788 – 24 July 1831), was a member of the House of Habsburg-Lorraine, and an Austrian clergyman and noble.

Born in the Pitti Palace in Florence, Tuscany, he was the youngest son of Emperor Leopold II and Maria Louisa of Spain.

Beethoven dedicated 14 compositions to Rudolph, including the Archduke Trio, the Hammerklavier Sonata, the Emperor Concerto and the Missa Solemnis.

[1] On 24 March 1819, aged 31, Rudolph was appointed Archbishop of Olomouc in the present day Czech Republic but then known as Olmütz which was part of the Austrian Empire.

He acquired a significant library of musical compositions, comprising over 18,000 works from 2,400 composers, now held by the Gesellschaft der Musikfreunde.