(Tales to Astonish I#19 (fb)) - The alien race native to the Fourth Galaxy were a warlike race that eventually became scientifically proficient, and set out to conquer other planets.  Choosing Earth as their next target, they sent Rommbu to demand a total surrender.

(Tales to Astonish I#19) - Rommbu arrived on Earth, his spacecraft landing in the path of a moving train.  When the train stopped, convicted criminal John Hunter made his escape.  Rommbu emerged from his ship, and demanded the surrender of Earth to his race.  He demonstrated his powers by using a ray gun to shrink two men to only twelve inches tall.  Meanwhile, Hunter had made his way onto Rommbu's ship unnoticed.  Rommbu then returned to his craft, and began to circle the Earth, awaiting the arrival of his armada.  There, he realized there was a human on board, and captured Hunter.  He used a mind-probing device to read the man's mind, and discovered him to be a criminal.  Believing Hunter's disregard for his fellow humans would be an asset, Rommbu recruited him to help find a safe place to land the ship to recharge its electromagnetic batteries.  Hunter, a former geologist, suggested the volcanic island of Watuna.  Rommbu didn't realize that Hunter had tricked him, and had timed their arrival on the island to coincide with the volcano's eruption.  As the volcano blew up, Rommbu desperately tried to escape in his ship, but the cataclysm apparently destroyed both him and John Hunter.

(Marvel Monsters: Monsters on the Prowl#1 (fb)-BTS) - Rommbu did not perish, and was captured by the Elder of the Universe known as the Collector.  Rommbu was placed in the Collector's zoo of giant monsters below Canada.

(Marvel Monsters: Monsters on the Prowl#1) - After an attack on the Collector by the Mole Man caused the freedom of the creatures, Rommbu was among many of the specimens to go on a rampage through New York City. They were defeated by a group of heroes that included the Hulk, the Beast, the Thing and Giant-Man.  Rommbu was personally defeated by the Thing. Mr. Fantastic had the Thing open a portal to the Negative Zone, where the creatures were all dumped.