The Iron Demiurge

The Iron Demiurge is a minor god in Warhammer Age of Sigmar. It was actually listed as a "God-Automaton" (a "Machine God" if you will?), and apparently smashed into disrepair and imprisoned inside a Stormvault.

Baseless Speculation

It could be a creation of Grungni, as he has previously created living clockwork beings. Also, "Demiurg" have been confirmed to be a subspecies of Squat/Kin from the Leagues of Votann in Warhammer 40K due to drifting cloneskein DNA samples, and as such, "The Iron Demiurge" could be Grungni's attempt at making a new mechanical son of his own now that Valaya's missing. It's unknown if The Iron Demiurge is related to the other Clockwork Beings Grungni created, the Cog-People of Odsin, who were embroiled in a mysterious disaster known as the "Winding Storm" and were then disowned by Grungni. It's possible The Iron Demiurge is the "Ancestor God" of the Cog-People of Odsin, and is responsible for whatever the events of the Winding Storm were, resulting in the need for The Iron Demiurge to be put down, yet still capable of being repaired, then imprisoned in a Stormvault. This could also be a possible point of contention between the Kharadron Overlords and other Dispossessed, as they count among their citizens "Gholemkind" and other living Clockwork automatons. It's possible that since the Kharadron Overlords reject Grimnir and Grungni, they still utilize a form of Cog-People even though Grungni has grown distrustful of them. This would further make the Kharadron Overlords similar to the Leagues of Votann, who are still friends with Artificial Intelligence robots despite the rest of humanity hating and fearing them because of the Cybernetic Revolt. The Iron Demiurge also sounds somewhat similar to "The Mad Core", a Votann who went mad after absorbing the dead of its League after the Tyranids slaughtered them to deny the Tyranids biomass.