The character first appeared in
Showcase #39 (July–August 1962) and was created by writer
Robert Kanigher and artists
Ross Andru and
Mike Esposito. Chemo debuted in a story called "The Deathless Doom" in
Showcase #39-40 (July–August & September–October 1962), being the adversary for DC Comics' new superteam the
Metal Men. The character returned in
Metal Men #14 (July 1965); #25 (May 1967) and #46-47 (July & September 1976). Chemo reappeared in
DC Comics Presents #4 (December 1978);
Superman #342 (December 1979) and #370 (April 1982);
Crisis on Infinite Earths #9-10 (December 1985-January 1986) and
Action Comics #590 (July 1987). Writer
Len Wein said in a 2006 interview: "I realized after doing that first story [with Chemo] that here was a villain that was a physical match against Superman, so I kept bringing him back". The character was reimagined in
Supergirl (vol. 4) #5 (January 1997) and then appeared briefly during the
Our Worlds At War storyline in
The Adventures of Superman #593-594 (August–September 2001) and in
Birds of Prey #36 (December 2001) and
Joker: Last Laugh #2 (December 2001). Chemo featured as a major villain in the limited series
Infinite Crisis #1-7 (December 2005-June 2006) and appeared in multiple forms in
Superman #663 (July 2007). The character also appeared in
Outsiders - Five of a Kind: Nightwing/Captain Boomerang (October 2007);
Salvation Run #1-7 (November 2007–June 2008) and in
Booster Gold (vol. 2) #13 (December 2008). Writer
Mike Conroy noted "where would comic books be without those flukes, those accidents of fate which, although inexplicable to science, result in innocuous materials having a far-reaching impact on the world outside the laboratory?". ==Fictional character biography==