We have a page for Huldrefolk but it only talks about the hulder in Forest of Shadows. They also appear in Frozen 2 book “Drôles de Créatures” (Funny Creatures if it was an English book). The Huldrer in that book is not named however it does give an image of what they look like.

In the same book it has a Fossegrim image. This one is in an imaginary story Kristoff tells, so its depiction may not be cannon in their universe. It doesn’t seem this wiki has a page for Fossegrims or for the character Fosse in All Is Found. I don’t have access to my book currently but if I remember correctly Fosse was tall with blonde hair? The Fossegrim in the French book is more like a goblin.

I can update the pages once I have a computer. Does anyone know of other appearances of these creatures?