Lupercio

Lupercio, the Baron of Sloth, is one of the many children of Pale Night. He is a monstrous, slug-like monster who dwells on the 128th layer of the Abyss, although he does not rule it due to his long periods of inactivity.

Sources:

https://en.wikipedia.org/wiki/List_of_demon_lords_in_Dungeons_%26_Dragons