Frederick I of Denmark was a king who ruled from 1523 to 1533. He was born in 1471 and was a member of the House of Oldenburg. Frederick I is known for his efforts to strengthen the Danish monarchy and for promoting the Protestant Reformation in Denmark, which led to significant religious changes in the country. During his reign, Frederick I faced challenges, including conflicts with the Danish nobility and issues related to the Swedish crown. His rule marked a transition in Danish politics, as he worked to consolidate power and navigate the complexities of regional politics in Northern Europe.