NK may refer to:

  • Nagorno-Karabakh
  • Natural killer cell
  • Neturei Karta, a group of anti-zionist orthodox Jews
  • New Kingdom
  • North Korea
  • Northrup-King Seed Company
  • Nippon Kaiji Kyokai
  • Nikšić, Montenegro license plates
  • Nordiska Kompaniet, a department store in Stockholm, Sweden
  • North Kesteven
  • Spirit Airlines, which has IATA code NK
  • Imerys, which has the Euronext ticker code NK
  • Neue Kerze aka new candle, an old photometric unit of luminous intensity