Background
Centuries ago on the planet Ma'aleca'andra, the Green Martians known as M'yrnn and Sha'sheen gave birth to twin sons. The bearing of twins was uncommon among the Martian culture, and as such, the first of the twins was named J'onn J'onzz, whose name means "Light to the Light." J'onn's brother, however, was born a mutant, bereft of a Martian's innate ability to communicate telepathically. He was named Ma'alefa'ak, whose name means "Darkness in the Heart."
As an adult, J'onn became a Manhunter (police officer) and married a Martian woman named M'yri'ah. The two established a modest home for themselves beneath the windswept Martian plains and gave birth to a daughter named K'hym.
Years passed, and J'onn's brother Ma'alefa'ak grew to despise everything about Martian culture. In an ambitious endeavor to commit full-scale genocide against his own people, he engineered a contagious virus known as H'ronmeer's Curse. The virus reacted to telepathic energy and carried from one Martian to the next whenever they elected to use their psionic powers. The plague responded to a Martian's innate fear of fire, causing them psychosomatic stress so intense, that their bodies and minds would literally burst into flame. J'onn desperately tried to keep his wife and daughter from using their mental gifts, but they were unable to do so, and thus ultimately contracted the virus. K'hym was the first to experience the symptoms, and M'yri'ah followed soon after. J'onn was anguished as he watched his family burning to death before his very eyes. The trauma of the event shattered his psyche, and nearly drove him mad.
Welcome to Earth
Meanwhile, on the planet Earth, a would-be scientist named Dr. Saul Erdel developed a transmitter machine based upon ancient Martian technology. Seeking to make contact with extraterrestrial life, he aimed his device towards the vicinity of Mars and activated it. The transmitter beam streaked across both space and time, striking the Martian Manhunter at a point in time several centuries before Erdel would even be born. The beam brought J'onn back to Erdel's natural time era, where he collapsed on the ground outside of the doctor's Colorado laboratory. Erdel brought the distraught Martian inside and attempted to nurse him back to health. The anguish of J'onn's mental state created a psychic bond between the two, and Erdel became aware of the events that took place on Mars. In an effort to heal J'onn's mind, Erdel used the mental link to fabricate a new history for the Martian. He created a back-story inspired by the writings of famous science fiction novelists such as Ray Bradbury and Edgar Rice Burroughs. Eventually, J'onn's sanity was restored, and he was prepared to function in this strange, new world. Erdel put the idea into his head that he should become a great champion, and thus J'onn adopted the heroic guise of the Martian Manhunter.
When J'onn shapeshifts into a human-like form, Erdel is shocked and suffers from a heart attack that kills him. Erdel asks J'onn for forgiveness for making him a prisoner of Earth. He is able to use his powers to fit in, adopting a human-like appearance and calling himself Detective "John Jones." He joins the police force, secretly using his alien powers to help the inhabitants of his new planet. It was during this time that he spent the next few years battling the menace known as the Idol Head of Diabolu. Deciding that he needed to free himself from his human persona in order to more effectively combat evil, he is ostensibly "killed in action" by the Idol Head, or so he wished it to appear. Shortly after giving up his John Jones persona, J'onn took the alias of Marco Xavier in order to infiltrate the international crime cartel known as VULTURE. Early on, the Manhunter from Mars adopted a more characteristically superheroic modus operandi, openly fighting crime in a green-skinned form.
Early Years
It was later revealed that Mars was dead when J'onn was taken, killed by a mental plague deliberately started by his brother Ma'alefa'ak. He took the identity of the Bronze Wraith, and fought crime with the Justice Experience.
The Martian Manhunter's history is intimately linked with that of the Justice League of America; he is a founding member of the team.