Manphibian is an extraterrestrial space faring scientist who first landed on Earth 1,000 years ago. He came from a pacifistic society with his female mate. Another male from his species murdered his mate upon arrival, with an extraterrestrial crossbow weapon in violation of their ancient ways. According to Manphibian, the murderer was the first to raise a hand or weapon in an untold number of eons. The blatant murder of his mate and blatant violation of their races ancient morals makes it known to Manphibian that the murderous alien is not a man but a monster. He justifies violence against him because while violence against fellow man is wrong the other creature is not a man but a monster and must be stopped.
Manphibian mentions that his enemy has escaped across hundreds of worlds for 10 centuries since their first encounter. Through unknown circumstances Manphibian became trapped underground for an unknown period of time. His justice was delayed until the moment he was released via a newly commisioned oil well. Upon reaching the surface drenched in oil he is attacked by the oil well workers but shrugs off their bullets and takes pity on them, for he is deadset on exacting vengeance on the other amphibious alien who murdered his mate/wife.
He finds the alien in a swamp/lagoon attacking a chauffeur and trying to abduct a woman. Manphibian sets upon the murderer of his wife in mad frenzy but his more insane enemy gets the better of him and takes the captured woman underwater in an attempt to escape Manphibian. Manphibian's heroic values shines through as he is deadset on not letting him kill again. He fights him for a while before realizing that the kidnapped victim is drowning and leaves the fight and returns to the surfacwe where he recognizes the oil well. He is beset by a fighter copter which fires incendiary missiles at him. Only his space-hardened skin protects him and his fragile cargo from the blast. Recognizing that they want to harm him and not the woman he escapes. Unfortunately, the woman is sent into a coma and may have suffered irreparable brain damage. The woman turns out to be the wife of the oil well magnate who was flying the copter which jeopardized his wife's life and he swears vengeance on Manphibian thinking that he is the cause of his wife's current condition.
Manphibian can now speak English it is not apparent how he learned it. He is also now a new member of the Legion of Monsters and has been part of SHIELD's monster unit along other freaks. He and the Legion saved a group of monsters from being killed by a monster killing group of assassins. He, the Legion, and the surviving monsters now live in the Morlock Tunnels as a safe hold.
However he was later captured by the Japanese monster killing force in which he finds out his kin have been killed by them and is forced to tell them where the monster safe hold is.
In his original appearance he mentions that violence has been forbidden for eons and that he rather study and document the humans desperate search for "black gold" (crude oil). This suggests that Manphibian is a scientist and that his wife or even his entire species are scientific space-farers.
He also mentions that the Elders say that "to seek vengeance would to become as mad as he" which means violence begets more violence and to think it would stop more violence is insane (insanity is endless repetition with the expectation of different results). He also apparently calls his God the "Prime Mover".