Ogremoch

Ogremoch is a powerful earth elemental.
As Shadi Moonglow explained to Maya (Session 33, he's known to the Elders of Hearthstone from legend as a threat to the balance of nature. He wanted to remake the plane in his own element (earth) but was kept in check by other powerful entities, despite swaying many to his cause at one time.

Saf has heard of Ogremoch - there was a miner in Steelforge who had gotten lost, was missing for a week, and turned up wild-eyed and raving. He said something about Ogremoch, but the locals didn't know the name; it was clear he was in fear for his life but couldn't articulate what he had experienced.