Fredrik Lange-Nielsen (13 May 1891 – 16 May 1980) was a Norwegian mathematician and insurance company manager.
He chaired the Norwegian Students' Society, edited Norsk matematisk Tidsskrift, and lectured at the University of Oslo.
He was chief executive of the insurance company Norske Liv for nearly twenty years, was elected member of several governmental commissions, and a member of the Norwegian Academy for Language and Literature from its establishment in 1953.