I did this for one of my modules in the university, starting from the character design until the final render, and it is one of my favorite projects so far as I love making creatures!
Gargagon is one of the stall owners in Bazaar of Nightmares, in the Underworld. His kind, Somnius, consume nightmare from children in the Upperworld. They sneak in at night, especially the powerful ones with high ability to chant spells and magic as disguise so the children won't wake up and see them. Some Somnius collect these dreams and store them in pots, and sell it at the bazaar freshly after. (That's why you cant remember your dream clearly sometimes, because your dreams are corrupted by Somnius) But Gargagon wants something more. He wanted to taste the good dreams, the beautiful ones, and extract them completely instead of the nightmares. He wants to rebel against the clan leaders who find it unethical to consume the good dreams only. Strangely, the more he consumes good dreams and leaving the children crying and scared at night.
I'm trying to create a tough look for Gargagon here, hence the skull-themed accessories and his rough appearance (with wounds and angry expression). My main reference was the orc from World of Warcraft!