The Hellkeepers are demons that guard the different levels of hell based on a particular sin (ie. wrath, gluttony, sloth, pride, greed, lust, envy). They use sand as their medium for keeping shape in the human world, except for Gluttony they use the liquid found primarily in the Leviathan.
Wrath:
Pride:
Sloth:
Greed:
Lust:
Gluttony:
HellVanguard
HellVanguard is like the big boss of all the other hellkeepers and a fight with one of these shadow like demons is sure to be a fun one