Jakob Nielsen
Jacob or Jakob Nielsen may refer to:
- Jacob Nielsen, Count of Halland, great grandson of Valdemar II of Denmark
- , Norway
- Jakob Nielsen (mathematician), Danish mathematician known for work on automorphisms of surfaces
- Jakob Nielsen (usability consultant), Danish web usability consultant
- Jakob Axel Nielsen, Danish lawyer and politician
- Jakob Nielsen (actor)
- Jacob Nielsen (cyclist), Danish cyclist
- Jakob Ahlmann Nielsen, Danish footballer