Uncle Rudolf is a character created for the Dutch Sesamstraat record albums. Uncle Rudolf, whose full name is Rudolf De Bont, is Bert's uncle. He is first mentioned in the 1981 album Bert en Ernie Vervelen Zich Nooit..., and makes his debut as a speaking character three years later, in In Een Uur de Wereld Rond.
He is married to Aunt Coleta. At one point in their relationship, Coleta left him for a few years. Rudolf plays the clarinet and the piano, and he often gets carried away in his sentimental, rather adult songs.
Bert is very fond of Uncle Rudolf, because he always brings books about the pencils Zipje & Zopje (Zippy & Zoppy). Ernie doesn't like how angry he looks, and how Bert always gets more presents from him.