Bernt Karsten Øksendal (born 10 April 1945 in Fredrikstad) is a Norwegian mathematician. He completed his undergraduate studies at the University of Oslo, working under . He obtained his PhD from University of California, Los Angeles in 1971; his thesis was titled Peak Sets and Interpolation Sets for Some Algebras of Analytic Functions and was supervised by Theodore Gamelin. In 1991, he was appointed as a professor at the University of Oslo. In 1992, he was appointed as an adjunct professor at the Norwegian School of Economics and Business Administration, Bergen, Norway.