The creature which would become known on Earth as Monsteroso was really an infant of a giant alien race. Traveling through space with his parents, Monsteroso accidentally released the lifecraft which proceeded to crashland on Earth in a remote jungle in Africa. Hearing of the wrecked spacecraft, an American circus owner went to the jungle to see if he could find a new attraction for his circus, despite the protests of his wife. The man had never seen anything as large as the wreckage of the spacecraft and nearby he found the body of Monsteroso. Finding no heartbeat or pulse, the man assumed the behemoth to be dead and decided to ship it back to America, where he could sell it to a museum.
The New York Museum of Natural History put Monsteroso on display but to everyone's horror, the monster soon opened his eyes. He then crashed through the solid brick wall of the building and went on a rampage on the city streets. The policemen's weapons were completely ineffective against the giant creature. The circus owner did not believe that Monsteroso was a threat, but that rather, he was curious of his new surroundings, but the police and his wife ignored him. After climbing to the top of the United Nations building, Monsteroso was struck with a harpoon containing a syringe full of sedatives. The weapon had the desired effect, making Monsteroso drowsy and he fell off of the top of the building and landed in the East River, where he floated fast asleep. While humanity congratulated themselves over their victory, an enourmous spacecraft came to Earth. When the doors opened, two figures which dwarfed Monsteroso appeared. They told the people that Monsteroso was their infant son and that they had been searching for him all over the solar system. They told the people that they were lucky that the child was not hurt and they departed again for the stars. The people all realized how extremely lucky they were that they had not managed to harm Monsteroso, despite their best efforts.
Years later, Monsteroso appeared as one of the inmates inside a secret deep-space torture prison controlled by the Jailer. A group of would-be escapees which included Black Bolt stumbled upon him and fought him until the telepath Blinky helped Monsteroso convey that he wasn't a threat. Following the Jailer's death, Black Bolt took Monsteroso in a ship and dropped him off in his planet, where he reunited with his family.
- Monsteroso possessed superhuman strength to an unknown degree, though he was able to smash through brick walls with ease.
- His hide is so tough that bullets bounced right off, though they did sting him a little.
- The original story has Monsteroso and his family as Orange, when the story was later reprinted this was changed to green/blue.
- 4 appearance(s) of Monsteroso (Alien) (Earth-616)
- 2 minor appearance(s) of Monsteroso (Alien) (Earth-616)
- 2 mention(s) of Monsteroso (Alien) (Earth-616)
- 4 image(s) of Monsteroso (Alien) (Earth-616)