On Mars, when a racial war broke out between the green-skinned Martians and the white-skinned ones, J'onn J'onzz, a leading citizen on his native world was placed in charge of the army. Having been defeated by the white Martians leader, Benn Blanx, J'onn was banished to a desert for thirteen years. During the first year, on the planet Earth, a would-be scientist named Dr. Mark Erdel built a transmitter machine. 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, and it brought J'onn back to Erdel's Colorado laboratory. When J'onn shapeshifted into a human-like form, Erdel was shocked and suffered a heart attack that killed him. As he was dying, Erdel asked J'onn for forgiveness for making him a prisoner of Earth.
J'onn was able to use his powers to fit into human society. He adopted a human appearance and called himself "John Jones." He became a police detective in the city of Middleton. For a long time, he worked as a policeman while secretly using his alien powers to solve cases and help people.
Some time later, the existence of the Martian Manhunter was accidentally revealed. From this point on, J'onn stopped hiding his superhero feats from the world, but he kept his double-identity as John Jones secret. It was at this time that he began to publicly appear in his green-skinned humanoid form.
In February, 1959, a panic is generated by the revelation of the presence of Martians (specifically from J'onzz and his enemy Commander Blanx and his followers) on Earth. Unable to cope with the situation alone, the Flash, summoned more experienced heroes, who would be an embryo of the Justice League.  One year later, J'onn J'onzz was one of the founding members of the (official) Justice League of America.
J'onn's career as a police detective was ended by the Idol Head of Diabolu. This evil statue expelled a deadly cloud. John Jones saved a child from the cloud, but in doing so he was engulfed by it. His fellow policemen believed he must have died. J'onn took this as an opportunity to abandon his double life. He allowed the police department (even Diane Meade) to believe he had died, and as the Martian Manhunter he even attended his own funeral.
After this, J'onn J'onzz and Zook began a quest to combat the Idol Head of Diabolu, which they finally managed to destroy.
J'onn served as a regular member of the Justice League of America. However, when a group of evil Martians led by General Blanx destroyed the surface of Mars, forcing all the good Martians to flee in a rocket, J'onn accompanied them into space in order to colonize a new world, leaving the Justice League. This new world, known as New Mars or Mars II, is the fourth planet from the sun of the star-system Cygnus.
Over the next few years J'onn was rarely seen, but he occasionally showed up to help the JLA. Eventually he returned to the JLA full-time. When his own people tried to invade the Earth, J'onn rebelled against them and prefered to remain with the Justice League on Earth.
- Martian Physiology: Martian Manhunter has been described as "the Swiss Army knife of superheroes." He possesses many of the powers of Superman. His powers come from his Martian physiology.
- Chameleon-like powers: Arguably one of the most incredible powers possessed by the Manhunter is the ability to shape-shift. He is able to literally control the molecular structure of his body and manipulate it into any shape he desires. He can form clothing and weapons with non-moving or non-functioning parts. There does not seem to be any limit to the number of people the Manhunter can imitate and has stood in as a double for many famous people. He is also able to change colors and turn himself into objects. J'onn once was able to mimic Superman's appearance and all his powers (and becoming invulnerable to fire!)- but an exposure to Gold Kryptonite eliminated this ability.
- Phasing: The Manhunter can phase through solid matter. 
- Superhuman Durability
- Superhuman Strength: Although not so strong as Superman, Martian Manhunter is able to hurt him in hand-to-hand combat.
- Superhuman Stamina
- Superhuman Speed
- Super Hearing
- Enhanced Senses
- Martian Vision: The actual nature of this power seems to vary depending on the reports. It has been seen to be a bolt of force, directed by the Manhunter's eyes causing considerable damage. It has also been seen to cause flammable objects to catch fire. J'onn can use his Martian vision to see people and objects that are invisible to others. For example, upon their first meeting, J'onn's power allowed him to see past Gypsy's metahuman camouflage ability; other effects are, at present, unknown.
- Telepathy: The Martian Manhunter is able to read minds and telepathycally communicate with others.
- Telekinesis: J'onn possesses the ability to move objects with his mind, which he described as ""molecular hypnosis" and "Martian mind-over-matter".
- Precognition: In some of his earliest adventures, the Martian Manhunter possessed the ability to see into the near future.
- Genius Level Intellect: The Martian Manhunter possesses highly advanced reasoning and logic capabilities, and uses them to great effect.
- Multilingualism: The Martian Manhunter is able to speak Martian and English.
- Tactical Analysis
- Hand-to-Hand Combat (Advanced)
- Vulnerability to Fire: The Martian Manhunter has a psychosomatic fear of fire. Exposure to fire, causes him to lose his powers and hurt him.
- Power Limitation: The use of Invisibility will temporarily deactivates all his other powers.
- This version of J'onn J'onzz, including all history and corresponding appearances, was erased from existence following the collapse of the original Multiverse in the 1985–86 Crisis on Infinite Earths limited series. Even though versions of the character may have since appeared, this information does not apply to those versions.
- In Earth-One continuity, the Martian Manhunter quit his tenure with the Justice League of America in Justice League of America #71 and did not officially return to active status until the reformation of the League in Justice League of America Annual #2. However, Post-Crisis continuity has retroactively re-inserted J'onn as an active League member for the entire span of the first iteration of the JLA.
- In his earliest appearances from 1955 to 1959, the Martian Manhunter was drawn completely hairless, with a beetle-brow forehead and shaded eyes. But throughout most of the Silver Age, he was drawn less as an alien and more as a human with green skin, with standard human eyes and dark eyebrows. This humanized look lasted for several years, until the late 1970s when he returned to his original beetle-brow appearance.
- Appearances of J'onn J'onzz (Earth-One)
- Images featuring J'onn J'onzz (Earth-One)
- Quotations by or about J'onn J'onzz (Earth-One)
- Character Gallery: J'onn J'onzz (Earth-One)
- ↑ House of Mystery #160
- ↑ Detective Comics #287
- ↑ 3.0 3.1 3.2 3.3 Who's Who: The Definitive Directory of the DC Universe #14
- ↑ taking into account that the last incarnation of the Justice League in the Pre-Crisis was the Justice League Detroit.
- ↑ 5.0 5.1 Detective Comics #225
- ↑ Detective Comics #273
- ↑ Detective Comics #275
- ↑ Detective Comics #311
- ↑ Justice League of America #144
- ↑ 10.0 10.1 10.2 Justice League of America #9
- ↑ Detective Comics #326. This was the end of the Martian Manhunter series in Detective Comics, which had lasted from #225 (November 1955) to #326 (April 1964). After this, the series moved to House of Mystery.
- ↑ House of Mystery #143-158
- ↑ House of Mystery #160-173
- ↑ Justice League of America #71
- ↑ Justice League of America #177
- ↑ Justice League of America Annual #2
- ↑ Justice League of America #42
- ↑ The Flash #175
- ↑ Crisis on Infinite Earths #10
- ↑ 20.0 20.1 DC Comics Presents #27
- ↑ Justice League of America #22
- ↑ Justice League of America #200
- ↑ 23.0 23.1 Detective Comics #226
|Justice League member|
This character is or was a member of the Justice League of America, or the Justice League in any of its various incarnations, sworn by a duty to act as guardians of America and the world by using their skills and/or superpowers to protect Earth from both interstellar and domestic threats.