Marit Nicolaysen (born 22 November 1953) is a Norwegian novelist, short story writer and children's writer.
She was born in Oslo.
She made her literary debut in 1985 with the novel I Frøyas tegn, where the protagonist "Sol" is a traveller who asks herself how Freyja in Norse mythology could be a goddess for both war and love.
She published the short story collection Tango med tiden in 1989.
Slusk (1993) and Himmelsnørr og kjærlighet (1995) are books for young adults.
She has written a number of children's books in the series Svein og rotta ("Svein and the rat"), illustrated by Per Dybvig, starting with Kloakkturen med Svein og rotta in 1996.
The series has been among the best selling books for children and young adults in Norway.
The 2006 family film Svein and the Rat is based on her novel.