Dark Horse:
The Conqueror Worm from the story of the same name was a Ogdru Hem sent by space-borne monsters to devour the Earth. It could turn people into frog monsters with its otherworldly breath and was preparing to devour the entire planet when it was defeated by Roger with aid from the ghost of Lobster Johnson. It was told that once the Worm had destroyed all life on earth, it would call the Ogdru Jahad from their prison.