What Is a Danish Nisse?
The bargain
The nisse is not a decoration and he is not friendly by default. The relationship in the folklore is contractual: the household leaves him porridge with butter, and in exchange the farm runs well. If the porridge stops, or the butter is left off, he takes it as an insult and the farm stops running well. That is the whole of the belief, and it is a working description of how a pre-industrial household explained its own luck.
Where he comes from
He descends from pre-Christian household gods, which is why he lives inside the building rather than out in the landscape like the lygtemand or under a church like the kirkegrim. Danish folklore was collected systematically from 1817 by Just Mathias Thiele at the Royal Library in Copenhagen and published as Danske Folkesagn between 1819 and 1823; Svend Grundtvig and Evald Tang Kristensen continued the work. Anything you read about the nisse that does not go back to that tradition is somebody's invention.
Nisse and Christmas
The red cap is the part that survived into the modern Danish December, which is how a household spirit who could ruin your harvest ended up on wrapping paper. The older figure is the one described above. The rest of the folk population is on the folklore creatures page, and the Danish-language walk that tells these stories meets at the University steps: the folk legends walk. If you do not read Danish, the English-language picture is honest about what is left.
Frequently asked questions
What is a nisse?
A Danish household spirit descended from pre-Christian household gods, no taller than a ten-year-old boy, in grey with a pointed red cap, living in the loft or stable.
What do you feed a nisse?
Porridge with butter. The folklore is specific: he is helpful if fed and destructive if neglected.
Is the nisse the same as a Christmas elf?
The red cap carried over into modern Danish Christmas, but the older figure is a household spirit. See Danish folklore creatures.