Olaf Nikolas Olsen (4 March 1794 – 19 December 1848, also spelt Oluf Nicolai or Nicolaj) was a cartographer and an officer of the Danish army.
He taught cartography at the Royal Cadet School and from 1830 on also at the new Army Academy.
In his function at the General Staff, he directed the publication of the Danish Ordnance Maps.
He also oversaw the publication of the first complete map of Iceland after a survey done by Björn Gunnlaugsson in the years 1831 to 1843.
This biographical article related to the military of Denmark is a stub.