Frederick VI, Duke of Swabia

Frederick VI of Hohenstaufen (February 1167 – 20 January 1191) was duke of Swabia from 1170 to his death at the siege of Acre. He was born in Modigliana, the third son of Frederick I Barbarossa and Beatrice I, Countess of Burgundy and brother of Henry VI, Holy Roman Emperor. Frederick was betrothed to the princess Constance of Hungary, but they never married. He died, aged 24, at Acre.