Synonyms for Barbarossa (same or very similar meaning)
WordNet sense 1 (Holy Roman Emperor from 1152 to 1190; conceded supremacy to the pope; drowned leading the Third Crusade (1123-1190)):
Frederick I, Frederick Barbarossa
WordNet sense 2 (Barbary pirate (died in 1546)):
Khayr ad-Din
From the ODE community, based on WordNet
add/edit