More Underworld critters, these are 2/3 of the friendly civilisations that live down there. The third group are basically impossible to make.
First, the Deceased. These guys are the reanimated corpses of those who have fallen in the depths below. Basically just friendly zombies (but don't actually call them that, it's considered offensive). Due to the fact they have no souls, they are bound to the Underworld until they get one.
Next are the Mushroom Giants. These fun guys (geddit?) get their names from their sheer size, averaging around 8 feet tall! They are also masters of the arcane and are willing to share their ways with any well-meaning being they come across. (Note: I took some liberties making this one, the actual 'head' of the giant is the cap)
Lastly, the ones I couldn't make are the Gearheads. They're automatons fuelled by arcane energy and are masters of invention. Their names are very literal, as they have floating gears for a head.