Otto I, Duke of Swabia and Bavaria (955–982), was the son of Liodolf of Swabia and his wife Ida, and thus a grandson of the Emperor Otto I and his Anglo-Saxon wife Eadgyth. His sister Mathilde was abess of a canoness monastery in Essen.
He was Duke of Swabia from 973 to 982 and was made Duke of Bavaria in 976, after Henry the Wrangler lost his Bavarian possessions rebelling against the emperor Otto II. He was a confidant of Otto II in the War of the Three Henries, and in 982 accompanied him on his Italian campaign against the Arabs. He survived the defeat of the Imperial army near Crotone on July 13 982 and a subsequent ambush by an Arab force. Otto assigned him to take the news of the campaign back to Germany, but he died en route on November 1 982 in Lucca. He was buried in Aschaffenburg.
His sister Mathild endowed a precious jewelled cross which is still kept in the treasury of Essen cathedral for his remembrance, the siblings are pictured on it.