On Golarion, the one eyed, four-armed stone demon Moxix is the Drinker of Human Hopes, one of the powers that accelerated Ghol-Gan’s slide into depravity, madness, and cannibalism. To that end, he’s well served by a number of abilities that batter the mind and crush morale. His physical crushitude—a bite, gore, and four slams each hitting at +29—ain’t bad either. Even his seeming vulnerabilities simply end up being a testament to his dark nature—for instance, when grievously wounded he gushes blood like an overfed tick, causing foes to slide and weapons to slip out of their wielders’ hands.
Oh, and his acidic breath weapon causes cannibalism. You failed your save? Whoops.
As written, Moxix is bound to an island peak and is the reason for that particular isle’s reputation for madness and disappearances. Here are some other non-Golarion options for this literal icon of horror:
The great stepped temples of the Tolchec people are supposed to be stairways to the gods. The Tolchecs have forgotten that these temples began as prisons for demons, with signs and glyphs worked into the stones to keep them trapped. When a Tolchec governor uses the stones of a crumbling temple to rebuild his palace, he does not realize he is freeing Moxix from his stone cage. Worse yet, Moxix’s sign begins appearing in the nearby settlement—not just on the stone blocks removed from the temple, but on cobblestones and bricks throughout the town—and people begin to grow confused…despairing…and hungry.
The Moxix of Malan hates the cyclops race he resembles. Once an elf of extraordinary power who felled giants as if they were trees, he was cast down and condemned to death when his cannibalism became too brazen for even the libertine Malan elves to ignore. When a dark whisper found him in his cell the night before his execution, Moxixelodrix was only too happy to strike a bargain. When the axe fell, Moxixelodrix’s blood poured onto the stones…and the stones rose up as the demon Moxix. Driven into the wilderness (but only after a great slaughter) he found brutish cyclopes waiting for him, calling him “Master.” He slew them…and the next batch…but the third group he spared, deciding he can tolerate the beasts until he has brought doom to the elves first.
Strange icons depicting a one-eyed figure begin appearing in the markets of Tau-Resh. No one knows their provenance, but those who own them eagerly display them. Then an order of masked priests begins denouncing the icons as blasphemous and attempts to confiscate them. Things get stranger when a paladin that touched one of the icons wakes up feebleminded, and at least one of the masked priests is revealed to be a snake-man. Investigation reveals an odd push-pull of forces at work—Moxix has awoken and seeks to resume his role as the Drinker of Human Hopes, but his serpentfolk followers jealously guard the power he offers.
—Inner Sea Bestiary 32–33
Jason Nelson gets the credit for adding Moxix to the Inner Sea Bestiary. Meanwhile, I should note that in the PFSRD Moxix is genericized as a “Stone Demon” and has no description; you’ll need the actual ISB for details on his history.