Frederick I (Danish and Norwegian: Frederik; German: Friedrich; Swedish: Fredrik; 7 October 1471 – 10 April 1533) was King of Denmark and Norway from 1523 and 1524, respectively, until his death in 1533, and earlier co-duke Duke of Schleswig and Holstein.
A member of the House of Oldenburg, he was the youngest son of King Christian I and Dorothea of Brandenburg. Not originally destined for the throne, he received joint rule in Schleswig and Holstein on reaching his majority in 1490 and resided chiefly at Gottorf Castle.