Otto I “the Great” (November 23, 912 - May 7, 973), son of Henry I the Fowler, king of the Germans, and Matilda of Ringelheim, was Duke of Saxony, King of Germany and arguably the first Holy Roman Emperor. (While Charlemagne had been crowned emperor in 800, his empire fell apart amidst succession disputes among his descendents, and following the assassination of Berengar of Friuli in 924, the imperial title lay vacant for nearly forty years.)

Otto succeeded his father as king of the Germans in 936. He arranged for his coronation to be held in Charlemagne's former capital, Aachen, and on being anointed by the archbishop of Mainz, primate of the German church. According to the Saxon historian Widukind of Corvey, at his coronation banquet he had the four other dukes of the empire, those of Franconia, Swabia, Bavaria and Lorraine, act as his personal attendants, Arnulf I of Bavaria as marshal (or stablemaster), Herman of Swabia as cupbearer (lat. pincerna or buticularius), Eberhard III of Franconia as steward (or seneschal), and Gilbert of Lorraine as chamberlain. Thus from the outset of his reign he signalled that he was the successor to Charlemagne, whose last heirs had died out in 911, and that he had the German church, with its powerful bishops and abbots, behind him. Otto intended to dominate the church and use that sole unifying institution in the German lands in order to establish an institution of theocratic imperial power. The Church offered wealth, military manpower and its monopoly on literacy. For his part the Emperor offered protection against the nobles, the promise of endowments, and a developing chancelry as an avenue to power as his ministeriales.

Italy had fallen into political chaos. On the death (950), possibly by poisoning, of Lothair of Arles, the Italian throne was inherited by a woman, Adelaide of Italy, the respective daughter, daughter-in-law, and widow of the last three kings of Italy. A local noble, Berengar of Ivrea, declared himself king of Italy, abducted Adelaide, and tried to legitimize his reign by forcing Adelaide to marry his son Adalbert. However, Adelaide escaped to Canossa and requested German intervention. Luitdolf and Henry independently invaded northern Italy to take advantage of the situation, but in 951 Otto frustrated his son's and his brother's ambitions by invading Italy himself, forcing Berengar to swear fealty, and then, having been widowed since 946, marrying Adelaide.

This marriage triggered another revolt. When Adelaide bore a son, Liutdolf feared for his position as Otto's heir, and in 953 he rebelled in league with Conrad the Red and the Archbishop of Mainz. While Otto was initially successful in reasserting his authority in Lorraine, he was captured while attacking Mainz, and by the next year, the rebellion had spread throughout the kingdom. However, Conrad and Luitdolf erred by allying themselves with the Magyars. Extensive Magyar raids in southern Germany in 954 compelled the German nobles to reunite, and at the Diet of Auerstadt, Conrad and Luitdolf were stripped of their titles and Otto's authority reestablished. In 955, Otto cemented his authority by routing Magyar forces at the Battle of Lechfeld.

After his death in 973 he was buried next to his first wife Edith of Wessex in the Cathedral of Magdeburg.