Otto II (955 – December 7, 983, Rome), called the Red, was the third German ruler of the Saxon or Ottonian dynasty. He was the son of Otto I, Holy Roman Emperor, and Adelaide of Italy.

Otto was named co-regent king of Italy and Germany with his father Otto I in 961 and became co-emperor in 967. He married Theophanu, niece of the Eastern Roman Emperor John I Tzimisces, on April 14, 972. Upon his father's death in 973, he was accepted as Holy Roman Emperor without opposition.

Otto spent his reign continuing his father's policy of strengthening imperial rule in Germany and extending it deeper into Italy. Henry II of Bavaria revolted in 974 and was not pacified until 978. The next year, Otto received the submission of both Bohemia and Poland. Also in that year, Lothair, king of France, invaded Lorraine, to which Otto renounced his claim in 980. With Germany secure, Otto invaded Italy that year, but was repulsed by the Arabs in 982. The next summer, he called a diet at Verona to confirm his son, Otto III, as king of Germany. He died later that year while campaigning against Venice. While he was in Italy, a Slavic invasion pushed the Germans west of the Elbe, but the realm was fairly strong at his death.