The Birth: One of the two survivors of the Martian race, J'onn was accidentally transported to Earth over thirty years ago. Upon arrival, he assumed the form of murdered police detective John Jones and did his best to fit in with human society. Joining with the other heroes of the age, J'onn was a founding member of the original Justice League as well as every successive incarnation of that group. He is now highly regarded as one of the most powerful and noble heroes among Earth's metahuman community. He was first drawn out in Detective Comics # 225 (November 1955), the brainchild of Joe Samachson and Joe Certa.

The Legend: Under the name of John Jones and other various aliases, J'onn works as a private detective for the JLA. Like all Martians, he has an aversion to open flame; must be because of their green skin. J'onn his a shapeshifter, he can assume any form at will. His powers include flight, super-strength, telepathy, invisibility, and super-speed, he can freely alter his physical shape and density. J'onn is able to project beams of energy through his red eyes ("Martian vision"). J'onn, has even helped Superman fight the Silver Banshee when Supes was nearly rendered comatose in his previous battle with her.
He has a deep appreciation of Earth cultures and maintains numerous human identities around the world. Besides Antartica, he operates from Z'onn Z'orr.
Recently, J'onn returned to visit Mars, unaware that Ma'alefa'ak (Malefic), the Martian villain behind the extermination of his race, is still alive and looking to complete his genocidal mission by killing J'onn. How this ancient rivalry will play out remains to be seen, as the Martian Manhunter increasingly engages in solo adventures away from his Justice League teammates.
While his various human guises help in his exploration of Earth society, J'onn remains very much the spiritual center of the JLA.

J'onn is considered the scourge of the underworld because of his dedication to truth and improving the lot of humanity everywhere, he is feared by underworld criminals worldwide. He has highly developed detective skills, advanced reasoning and logic capabilities, excellent human relations skills, highly developed empathic abilities and is fluent in many Earth languages. He is considered a Class 3 telepath. He is able to read the mind of any normal human with no difficulties, assuming that human is not insane, of normal willpower and has received no special telepathic block training.

In many areas of the world, J'onn J'onzz is more well known than even Superman.