Gustav Johan Fredrik Dietrichson (8 April 1855 – 19 March 1922) was a Norwegian theologian and priest. He served as bishop of both the Diocese of Hålogaland and the Diocese of Hamar. Dietrichson was born in the state of Wisconsin. His parents, Gustav Fredrik Dietrichson (1813–1886) and Pauline Christine Sørine Alette Henriette Preus (1819–1900) were Norwegian immigrant to the United States. He came for a clerical family. His maternal uncle, (1814–1878), had immigrant from Norway in 1850. Preus served as the first President of the Norwegian Synod prior to returning to Norway in 1870 where he served as vicar of Tvedestrand and Holt in Aust-Agder until his death.