The Nix... male manifestation of a water sprite.
The Neck/Nixie (German: Nix/Nixe/Nyx) are shapeshifting water spirits who usually appear in human form. The spirit has appeared in the myths and legends of all Germanic peoples in Europe.
The German Nix and his Scandinavian counterparts are males. The German Nixe or Nixie is a female river mermaid