is a southern Danish city, seat of the Guldborgsund kommune. It belongs to Region Sjælland. The city lies on Falster, connected by the 295-meter-long Frederick IX Bridge over the Guldborgsund waterway to the island of Lolland. The town has a population of 16,464 (1 January 2011). Including the satellite town Sundby on the Lolland side, with a popualation of 2,872, the total population is 19,336.
Nykøbing Falster was founded around a 12th-century medieval castle.