Nielsen [IPA 'nelsn], is a Danish patronymic surname, literally meaning son of Niels, Niels being the Danish version of the Greek male given name Νικόλαος, Nikolaos (cf. Nicholas). It is the secon most common surname in Denmark, shared by about 5% of the population. It is also used in Norway, although the form Nilsen is more common. In Sweden the parallel form is Nilsson. Nielsen is also in use in the Faroe Islands. The frequent occurrences of Nielsen as a surname outside Denmark is due to immigration.