Urho Jonas Castrén (30 December 1886, in Jyväskylä – 8 March 1965, in Helsinki) was a judge, serving for 27 years as the President of the Supreme Administrative Court of Finland.

During the constitutional crisis of 1944,[1] Castrén, representing the National Coalition Party, became Prime Minister of Finland briefly.

He attended the Lyceum of Jyväskylä, completing his classics studies in 1904 and earning a legal degree in 1907.

Between 1918 and 1927 he taught at the Agriculture and Forestry division and Political Science Department of the Faculty of Law at the University of Helsinki as a specialty teacher.

In 1914, he became a legal counselor and a member of the Helsinki City Court, where he remained until 1917 when he transferred to the Residential Tax Assessor's office.