Fauns and Satyr
In the Grim North these faerie creatures are somewhat divergent from the classical myth and therefore the Monster Manual.
In the shadowy forests they lurk, hoof and horn, twisted hybrids of beast and man, for this is not the friendly Mr Tumnus faun nor even the chaotic Pan satyr. These are the dark manifestations of the forest itself, they are malign faeries, revelling in disorder and bloodshed. And wine, because all fey creatures love wine.
Their banquets take place in the deepest woodland glades where they drink themselves into insensate rage and feast on human flesh. Their dances are preludes to slaughter and they do not play the pipes but instead march to the sound of harsh, braying horns cut from the bodies of their fallen brethren. When sufficiently drunk and worked up into a frenzy, they spill forth from the trees to lay waste to the villages of man.
In game terms a Faun is a 1HD monster with damage as weapon, probably a spear. They stand about five feet tall, manlike but with goat's legs and small straight horns. Their faces are a mix of bestial and human looking and they typically sport very long, straight hair.
A Satyr is generally greater than six feet tall, 2-3HD on average, and very strong weapon +1 damage. They have the shaggy goat's legs but the torso of a heavily built man. They often sport heads that are truly bestial shaped like that of a goat, ram or deer. Their horns are large, often curving like a ram's or antlers like a deer. They favour axes and spiked maces and do not use missile weapons except those that can be thrown.
They often consort in mixed war bands frequently including other dark faeries such as Centaurs and the odd Minotaur. They hold a deep hatred for mankind and all other non bestial faerie creatures, especially (gasp,surely not) elves.
Surely the rumours that they keep Owl Bears as pets and war beasts are exaggerated. I mean come on, Owl Bears?