Metamorpho (real name Rex Mason, also called The Element Man) is a fictional character, a superhero in the DC Comics Universe. He is a founding member of the Outsiders, and has also joined multiple incarnations of the Justice League.
Metamorpho's creator, Bob Haney, had seen success with DC Comics in 1963 with the titles Metal Men and Doom Patrol, featuring bands of superheroes exhibiting fantastic powers. Under the editorial management of George Kashdan, Haney was asked to capitalize on these titles' popularity with a similar character. Metamorpho, the Element Man, debuted in The Brave and the Bold #57 (January 1965). As first conceived, Metamorpho was a parody of the fantastic characters that populated comic books in the 1960s. Artist Ramona Fradon was coaxed out of maternity-retirement to illustrate Metamorpho's first appearances. The popularity of Metamorpho's appearances in The Brave and the Bold led to a 17 issue ongoing series between 1965 and 1968. Metamorpho also appeared during this time in two issues of Justice League of America (#42 & #44, the second of which is an appearance so brief that no one seems to remember it), but became the second superhero to decline an invitation to join that organization (Adam Strange being the first).
In 1975 Metamorpho appeared in 1st Issue Special #3, a brief series consisting of one-shots of new and established DC comics characters. That issue was written by Bob Haney and illustrated by Ramona Fradon, Metamorpho's original creators.
After becoming a charter member of the Outsiders in 1983, and member of the European branch of the Justice League International, he received his own 4 issue mini-series in 1993.
In 2005, DC Comics reprinted Metamorpho's early The Brave and the Bold appearances and the entirety of the 1965 series as one of the company's volumes of Showcase Presents.
In 2007, Dan Jurgens launched the 6 issue series Metamorpho Year One.
As part of a Wednesday Comics, Neil Gaiman wrote a twelve-page Metamorpho story that Mike Allred illustrated
Rex Mason was an adventurer who was hired by business tycoon Simon Stagg to retrieve a rare Egyptian artifact. Mason also started dating Stagg's daughter, Sapphire Stagg.
In an Egyptian pyramid, Rex Mason was knocked out by Simon's brutish bodyguard, Java, and eventually exposed to a radioactive meteorite called the Orb of Ra, which transformed him into the Element Man. He gained the ability to shapeshift and change himself into any element found in the human body, or any combinations thereof. It was also established in his origin story (see: The Brave & The Bold #57) that he was virtually invulnerable in his inert (untransformed) state. Later, it was revealed that Mason was but one of many metamorphae, created by the sun god Ra to serve as warriors in his battle against the god Apep, "the serpent who never dies."
Metamorpho, unlike other super-humanoids described in DC Comics, could not assume a fully human, normal appearance. As such, he regarded his metamorphic powers as a disease and sought a cure for his condition. (A common theme in science fiction and comic books.) He considered himself a non-human freak because of his abilities and wanted to be restored to normal. For that reason, he rejected an offer of membership that the Justice League of America extended to him.
Metamorpho briefly had a crimefighting partner: a woman named Urania "Rainie" Blackwell who deliberately exposed herself to the Orb and gained its powers, calling herself Element Girl. She worked with him on a number of cases before her unrequited attraction to him became too much for her. Blackwell's power was removed, resulting in her death, at her own request by the sun god Ra, with assistance from Death, in Neil Gaiman's Sandman.