Saint Otto or Blessed Otto may refer to:
Saint Ottone Frangipane (died 1127), Italian monk and hermit Saint Otto of Bamberg (died 1139), German missionary and bishop Blessed Otto of Freising (died 1158), German bishop and historian Saint (died 1220), Franciscan martyred in Morocco with four companions Blessed Otto Neururer (1882–1940), Austrian priest who died in a Nazi concentration camp