Didrik Arup Seip (31 August 1884 – 3 May 1963) was a professor of North Germanic languages at the University of Oslo. He earned his doctorate (dr.philos.) in 1916 and was appointed professor the same year, retiring in 1954. Together with Herman Jæger, he edited and published the collected works of Henrik Wergeland in 23 volumes (Samlede Skrifter : trykt og utrykt, 1918–1940). From 1937 until 1945, he served as the rector of the university. He was an honorary doctor at the University of Hamburg (1938) and at Sorbonne (1945). He obtained the Norwegian Order of St. Olav (1945).