Andreasen and the parallel form Andresen (Norwegian cognate Andreassen) are Danish-Norwegian patronymic surnames meaning "son of Andreas". It has a similar origin as the name Andersen. It may refer to:
Christian Andreasen, Danish footballer
Emil Andreasen (1895 – 1972), Danish boxer
Frank Andreasen, Danish darts player
George Andreasen, American orthodontist
Heidi Andreasen, Faroese paralympic swimming silver medalist
Lawrence Andreasen, American athlete
Leon Andreasen (born 1983), Danish footballer
Marta Andreasen (born 1954), Argentina-born member of the European Parliament
Nancy Coover Andreasen, American neuroscientist
