He has been borrowed from Näcken in Scandinavian folklore.

He is principally known for pulling young children into the depths, if they lean over bridge railings, or otherwise look into water surfaces to see their own reflection. Näkki is a fine example of a spirit enlisted by parents to guide children away from unsafe practises.

It is also said that although Näkki is very beautiful from the front, his backside is hairy and extremely ugly. Näkki is also called Vetehinen.