Conrad (25 March 1252 – 29 October 1268), called the Younger or the Boy, but usually known by the diminutive Conradin (German: Konradin, Italian: Corradino), was the Duke of Swabia (1254–1268, as Conrad IV), King of Jerusalem (1254–1268, as Conrad III), and King of Sicily (1254–1258, de jure until 1268, as Conrad II).
Conradin was born in Wolfstein, Bavaria, to Conrad IV of Germany and Elisabeth of Wittelsbach. He is sometimes known as Conrad V of Germany. Though he never succeeded his father in Germany, he was recognized as king of the Germans, Sicily, and Jerusalem by German supporters of the Hohenstaufens in 1254.
Having lost his father in 1254, he grew up at the court of his uncle and guardian, Louis II, Duke of Upper Bavaria. His guardians were able to hold Swabia for him. Jerusalem was held by a relative from the royal house of Cyprus as regent. In Sicily, his father's half-brother Manfred continued as regent, but began to develop plans to usurp the kingship.