Back when I was developing my demon characters I spent a lot of time in Gluttony (go figure) and I had an idea of a group of beings that were forces of nature so to speak, beings that don't really have a reason of existing yet they do, keep in mind these are all monsters that are not to be crossed (except for one).

In order of lethality:
MOUNTAIN BEAST
She is a passive demon and is too fat to be any real threat, she's 25 ft tall and 50ft long, she also sports a massive udder. She governs a stray tribe of Gluttony demons in a mountainous region far from Goteaah's Mount, The Mountain Beast's clan of demons are leaner, more intelligent and ruthless should any threat befall their Queen, the reason for this is because they were raised on Mountain Beast's milk. Unlike Gorteaah's demons which are fatter, dumber and overall simple minded raised on lactation that is more rich with fat, Mountain Beast's milk is rich in nutrients due to her vegan diet, she feeds on the large leaves of a local tree that grows in that region. She is a benevolent leader with only two rules: she gets milked once a day and her breast milk is off limits, only allowed to pregnant women for strong offspring and as a rite of passage into motherhood. And children actually run free in this village and are allowed to grow naturally.

THE HARPY
The Harpy is a classic creature of myth, in Gluttony she is a vicious creature that travels the realm hunting for game. She is 25ft tall with a 100ft wingspan, despite her predatory nature she's also a messenger for Gorteaah, reporting any anomalies in exchange for food of course.

MOTHER SLUG
The original Queen of Gluttony, she's a repugnant monster that only cares for herself, she lives underground in her slug nest, signs of her territories include dead trees and dry soil. She's a massive 100ft long, a true glutton, she often resorts to eating her own slugs. The slime secreted from her body is a paralyzing agent that numbs the muscles of her prey, the saliva she spews is acidic and is to break down her food into sludge like slime for easier consumption. On many occasions she has antagonized Gorteaah and her keep, even claiming she can claim the title of "Arch Demon" from Gorteaah's daughter. Although...

OCTO MASTER
Octo Master is the only demon of this group that is actually worthy of claiming the title of Arch Demon, she's 200 ft long from the top of her head to the tip of one of her tentacles, she is the third strongest demon in all of Gluttony being the apex predator of the seas but, there in lies the issue, she is ocean bound and cannot be on land for too long without a body of water to eventually return to. It also helps that she has no interest in claiming title of arch. The creatures of the sea are far more territorial than those found on land but Octo Master cares very little of this fact, claiming all to be her food. Her tactics are to simply overpower her prey, using her tentacles to constrict her prey or to slam them against her prey, the sheer brute strength she possesses is astounding. Gorteaah first discovered her a long time ago while out for a swim and was pulled further down under by her ankle, after she was bitten in the leg she grew larger and pulled Octo Master out of the water, she struggled immensely to return to the ocean and while Gorteaah could have easily swallowed the creature, she let her go out of respect.

Don't ask me about their weights, they huge.