Conrad IV of Germany

Conrad (25 April 1228 – 21 May 1254), a member of the Hohenstaufen dynasty, was the only son of Emperor Frederick II from his second marriage with Queen Isabella II of Jerusalem. He inherited the title of King of Jerusalem (as Conrad II) upon the death of his mother in childbirth. Appointed Duke of Swabia in 1235, his father had him elected King of Germany (King of the Romans) and crowned King of Italy (as Conrad IV) in 1237. After the emperor was deposed and died in 1250, he ruled as King of Sicily (Conrad I) until his death.

Source: Wikipedia — https://en.wikipedia.org/wiki/Conrad_IV_of_Germany