Frederick II, Duke of Swabia

Frederick II (1090–1147), called the One-Eyed, was the second Hohenstaufen Duke of Swabia, ruling from 1105. With his brother Conrad he enlarged the family lands, and in 1116 Henry V appointed the brothers regents during his Italian campaign.

After the Salian line ended in 1125 Frederick stood for the crown but lost to Lothair II; a feud over the Salian inheritance cost him an eye and his royal hopes. He fought Lothair until submitting at Bamberg in 1135.

After Conrad became king in 1138 he supported him against the Welfs. By Judith of Bavaria he fathered Frederick Barbarossa, and died at Alzey in 1147.