Johan Collett Müller Borgen (28 April 1902 – 16 October 1979) was a Norwegian author, journalist and critic.
He was born in Kristiania. He was married to Annemarta Borgen. Under the pseudonym of Mumle Gåsegg (Mumble Goose-egg) he wrote shorter articles in the newspaper Dagbladet, particularly during World War II. His articles were ironic and derogatory of the Nazi government, and he kept this up for a long time before being found out. In the end though, he was caught and sent to the prison camp Grini. His best-known work is the novel Lillelord (1955). Borgen was editor of the literary magazine Vinduet ("The Window") 1954-1959.