An alp is a supernatural being in German folklore.
Nachtmahr (Night-mare), by Johann Heinrich Füssli (1802), depicts an alp sitting on the sleeper's chest, with a mare staring through the background.
In German heroic legend, Alberich is a dwarf. He features most prominently in the poems Nibelungenlied and Ortnit. He also features in the Old Norse collection of German legends called the Thidreksaga
Alberich seduces the king's mother (a scene from Ortnit, 1480 woodcut)
Alberich (with whip) drives on the Nibelung dwarfs, who collect gold and other treasures. (Arthur Rackham, 1910)
Siegfried wrestles with Alberich (Julius Schnorr von Carolsfeld, 1843)