奥托一世（Otto I，912年11月23日－973年5月7日），又译鄂图一世，东法兰克国王（936年—973年在位），罗马帝国皇帝（962年加冕）。史称奥托大帝（Otto der Große）。东法兰克国王亨利一世之子，母为Ringlheim的玛蒂尔达。先当选为萨克森公爵，936年由东法兰克部落公爵选为国王。936年7月31日，美因茨大主教希尔德贝特在亚琛为奥托一世加冕。

奥托一世坚持他对各部落公国均拥有最高权力，公爵们为此常常造反。938年奥托一世镇压了由法兰克尼亚公爵埃贝哈德和巴伐利亚公爵埃贝哈德联合发动的叛乱。929年—941年镇压其弟巴伐利亚公爵亨利一世的叛乱。944年奥托一世封自己的女婿康拉德（“红公爵”）为洛林公爵，此人后来与他反目。946年奥托一世率军干涉法国内战，先支持反对国王的法兰西公爵（卡佩家族的成员），后转为支持西法兰克国王路易四世。949年封次子鲁道夫为士瓦本公爵。

Otto I (23 November 912 – 7 May 973), also known as Otto the Great, was German king from 936 and emperor of the Holy Roman Empire from 962 until his death in 973. He was the oldest son of Henry I the Fowler and Matilda.

Otto inherited the Duchy of Saxony and the kingship of the Germans upon his father's death in 936. He continued his father's work of unifying all German tribes into a single kingdom and greatly expanded the king's powers at the expense of the aristocracy. Through strategic marriages and personal appointments, Otto installed members of his family in the kingdom's most important duchies. This reduced the various dukes, who had previously been co-equals with the king, to royal subjects under his authority. Otto transformed the Roman Catholic Church in Germany to strengthen the royal office and subjected its clergy to his personal control.