Nisse, pronounced nesa, is a typical Scandinavian Christmas character, centuries old. Unlike Santa Claus this character does not live on the North Pole. In fact, nisser live right in your backyard, whether in your barn, stable or nearby forest. And they will move in with you to live in your attic.
The nisse looks like a human being but is half the size or even smaller. They act and behave like humans, wanting to protect the farm, the animals, and the crop. A pre-Christian figure they act as spirit helpers. However, being temperamental, they will play tricks on you, if offended. Basically, if your grain is eaten or an animal dies, blame the nisse.
When it is winter and the fields lay dormant, the nisse hides out in the attic and to keep him happy, it is recommended to set out a bowl of porridge for him. Like humans celebrate Christmas, the nisse will, too, and expects to be given gifts. After a year of being good, helping out around the farm, the nisse is being rewarded.
A famous Christmas song: På loftet sidder nissen med sin risengrød (The nisse sits in the attic with his porridge) tells the story about keeping your nisse happy.
The modern day nisse has taken on more human character and has even been portrayed as life size humans living like humans but out of sight from real humans. However, it is custom for nisser to wear only red and grey outfits with a red pointed nissehue (hat) and wooden clogs.
Typically, you decorate your house with nisser in all shapes and sizes. Also, today the Scandinavian Santa Claus is a nisse morphed into a life size Julemand (Christmas Man) and will come to your door with gifts in his sack (naturally, a family member dressed up). No flying reindeer or Santa Claus in a sleigh coming down your chimney, although he is known to the nisse;)