The Mighty Thor no.154, July 1968 from Marvel (indicia indicates Atlas Magazines Inc). Jack Kirby and Stan Lee serve up one of the greatest Thor epics of all time. Hela pays a visit to Sif’s hospital room while she hangs in the balance from Loki’s onslaught.
Meanwhile, Ulik the Troll seeks revenge against the Asgardians. Searching deep in the bowels of the Earth, Ulik discovers a prison with a warning from Odin. “Let the universe tremble! The Mangog lives again!” shouts the beast that emerges from the shattered cell. Ulik, who recently held his own against Thor, realizes that this ancient creature’s power dwarfs his own. This terrifying monstrosity’s origin is obscured in this first appearance; his true power levels only hinted at as he explodes to the surface.
Cover art is by Kirby and Vince Colletta, though another inker may have assisted with the background collage.