Nicolaysen is a surname. Notable people with the name include:
Nicolay Nicolaysen (1817–1911), Norwegian archaeologist Julius Nicolaysen (1831–1909), Norwegian professor of medicine Nicolay Nicolaysen Sontum (1852–1915), Norwegian engineer, businessperson and contractor Wilhelm Nicolaysen (1869–1944), Norwegian barrister and businessperson
See also Nicolaisen, surname