Birger Kristian Eriksen (17 November 1875 – 16 July 1958) was a Norwegian officer (with the rank of Oberst) who was instrumental in stopping the first wave of Gruppe 5 of the German invasion force outside Oslo.
Eriksen was the commander of Oscarsborg Fortress when Nazi Germany attacked Norway in the early hours of 9 April 1940.
He gained lasting recognition for ordering the fortress under his command to open fire on the vanguard forces of Operation Weserübung, sinking the 16,000 ton heavy cruiser Blücher.