Otto or Oddo (died 30 November 912) was a Saxon nobleman; by later authors, he is often called Otto the Illustrious. The younger son of Liudolf, Duke of Saxony and his wife Oda, Otto presumably became duke of Saxony shortly before his death, but no details are known.

According to Widukind of Corvey, Otto was offered the kingship of the East Franks in 911 and did not accept it, but the truthfulness of this report is considered doubtful. He is named as count of South Thuringia in 888, and as count of the Eichsfeld in 908; he was also lay abbot of the Monastery of Hersfeld. Otto is buried in the monastery church of Gandersheim. His son Henry, later to be King Henry the Fowler, succeeded him as duke of Saxony.