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"No wonder he always looked up to you."
"Me? He's the one who had it made."
"No. He watches you on the news all the time. He still misses it. Being in action, saving people's lives. I think he'd trade places with you in a minute.
Sapphire Stagg
John Stewart[1]

Metamorpho, real name Rex Mason, was an old Marine Corps friend of John Stewart and was transformed by the machinations of Simon Stagg. He became a member of the Justice League after the Thanagarian invasion.


Rex Mason worked for Simon Stagg until he fell in love with Simon's only daughter, Sapphire. Knowing Simon would never approve of their relationship, the two kept it secret from Simon for a while. Rex met up with his old friend, John Stewart (who calls him "Mace") when GL prevented the runaway train Rex was on from crashing. Rex introduced John to Sapphire and told him of their relationship, including the fact that Simon didn't know about it.

Batman soon discovered the incident on the train was caused by chemicals being illegally transported on the train by Simon Stagg's company. When Rex learned this, he confronted Stagg, who didn't deny his suspicions, but warned him not to stick his nose in the matter, as he 'made' Rex, and could just as easily unmake him. Later when Simon visited Sapphire, he was shocked to find Rex there. The couple told Simon of their relationship, followed by Rex announcing his resignation from Simon's company so he could take a job in Chicago... and take Sapphire with him. Reeling from all this news, Simon nevertheless composed himself and told Rex and Sapphire they had his blessing.

Later, as Rex was cleaning out his desk, Simon arranged events so that a false alarm sounded and drew Rex into a room where he was encased in a tube and subjected to Stagg's experiment. Rex was made a test subject for Stagg's project to create a "chemical man" who could survive in any environment. The project was code-named "Metamorpho."

As a result of the experiment, Mason could now transmute any part of his body into any element or chemical. Mason was distraught over his freakish new appearance and literally had a meltdown as he tried to cope with his new abilities. Stagg manipulated Mason into fighting Stewart and nearly killing his old friend.[1] Then Superman, Hawkgirl, Batman and J'onn J'onzz arrived on the scene. Metamorpho held his own against the League, which delighted Stagg, who was secretly across the street videotaping the encounter in order to impress potential investors.

Metamorpho eventually fled from the battle and confronted Sapphire in their home as to her "affair" with Stewart (which was just another Stagg lie). Unafraid, Sapphire slapped him and reassured him that she still loved him, regardless of his transformation and new appearance. Realizing that he had been played for a fool, Mason located Stagg in one of his laboratories and vowed that Stagg would never do to anyone else what he did to Mason. Metamorpho started destroying Stagg's equipment, and in doing so, inadvertently caused an accident that saw Stagg's mind transferred into a giant chemical monster. The monster rampaged through the city and kidnapped Sapphire. However, with the help of the League, Metamorpho turned himself into a polypeptide capable of neutralizing the monster. Knowing that he probably wouldn't survive the process, Metamorpho heroically dove into the monster anyway and released the polypeptide to save Sapphire. The gambit worked and seemingly, neither Metamorpho nor the monster survived. Sapphire shed a tear for Rex, which landed in some of the polypeptide residue. All the residue then pooled together and rose up, reconstituting Metamorpho, much to the joy of Sapphire and the relief of Stewart.[2]

Some time later, Superman was seemingly disintegrated by Toyman and presumed dead. (Actually, he had been flung into the far future.) At his wake, the League discussed potential replacements, with Stewart suggesting Metamorpho. It became a moot point when Superman returned to his own era, though Metamorpho did join the expanded League following the Thanagarian invasion.[3][4]

Powers and abilities[]

Rex's mutagen exposure augmented his entire physical body.

  • Shapeshifting: Rex can stretch, bounce, elongate, control, reshape his body as if it were made of polymer or liquid. He can even shift his mass into shapes like weapons and blunt objects.
  • Transmutation: Rex can transmute his body to any of a wide variety of liquid, gas or solid elemental compounds and/or materials he can reform to his will. Metamorpho can alter the shapes and consistencies of these elements, combining them to form complex compounds. Even being able to assume forms of vapor, fluidic or concrete matter states. Rex having once transmuted his left arm into pure Kryptonite, a substance with elements not found on the earthly periodic table. He could even project hypergolic facets that explode on contact. As well as convert himself into polypeptides and other organic substances; some of the most complex substances known to man.
  • Enhanced Durability: The nature of Rex's body provides him with degree of protection offering damage resistance from blunt attacks and energy attacks.
  • Enhanced Strength: While not on Superman's level, Rex is superior in physical strength than he was as a human.


Justice League

Justice League Unlimited


  1. 1.0 1.1 Uhley, Len (writer) & Riba, Dan (director) (October 4, 2002). "Metamorphosis, Part I". Justice League. Season 1. Episode 22 (airdate). Episode 22 (production). Cartoon Network.
  2. Uhley, Len (story) & McDuffie, Dwayne (teleplay) & Riba, Dan (director) (October 11, 2002). "Metamorphosis, Part II". Justice League. Season 1. Episode 23 (airdate). Episode 23 (production). Cartoon Network.
  3. McDuffie, Dwayne (writer) & Lukic, Butch (director) (November 29, 2003). "Hereafter, Part II". Justice League. Season 2. Episode 20 (airdate). Episode 44 (production). Cartoon Network.
  4. Berkowitz, Stan (writer) & Dos Santos, Joaquim (director) (July 31, 2004). "Initiation". Justice League Unlimited. Season 1. Episode 1 (airdate). Episode 1 (production). Cartoon Network.

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