Jakob Nielsen

Jacob or Jakob Nielsen may refer to:


 * Jacob Nielsen, Count of Halland (died c. 1309), great grandson of Valdemar II of Denmark
 * , Norway (1768-1822)
 * Jakob Nielsen (mathematician) (1890–1959), Danish mathematician known for work on automorphisms of surfaces
 * Jakob Nielsen (usability consultant) (born 1957), Danish web usability consultant
 * Jakob Axel Nielsen (born 1967), Danish lawyer and politician
 * Jakob Nielsen (actor) (1900-1978)
 * Jacob Nielsen (cyclist) (born 1978), Danish cyclist
 * Jakob Ahlmann Nielsen (born 1991), Danish footballer