Read more about Dev-Em at: Wikipedia

Official Site: DC Comics

Dev-Em is a fictional character who appears in DC Comics. He first appeared in Adventure Comics #287 (June 1961).

In the pre-Crisis on Infinite Earths continuity, Dev-Em is a Kryptonian juvenile delinquent who took Jor-El's warnings of Krypton's impending doom seriously enough to place himself in suspended animation in an orbiting space capsule. When the planet Krypton exploded, Dev-Em's ship was blasted into space, where it eventually landed on Earth. Dev-Em imprisons Superboy in the Phantom Zone and assumes his identity in an effort to destroy the Boy of Steel's reputation. Eventually he frees Superboy and departs from the twentieth century, traveling through time to finally settle on the more advanced Earth of the 30th century. Since the people of Smallville will not believe Superboy's story of the impostor, he has to use a cover story that he was acting under the influence of Red Kryptonite to restore his reputation.

Dev-Em returns in Adventure Comics #320 (May 1964), where it is revealed that the so-called "Knave of Krypton" has reformed and joined the Interstellar Counter-Intelligence Corps of the 30th century. He is reluctantly offered membership in the Legion of Super-Heroes but turns it down. Despite his occasionally abrasive nature, Dev-Em aids the Legion on several occasions, most notably in the "Great Darkness Saga" against Darkseid.

In the limited series Who's Who in the Legion of Super-Heroes #1 (April 1988), his post-Crisis background was changed. Since Superman is now the only survivor of Krypton because of the Superman reboot, his entry in this encyclopedia-like series states that he is David Emery, a resident of Titan, home world of Saturn Girl, who uses his mental powers to give himself Kryptonian-style super powers. This origin is never used in any actual comic story.

Dev-Em has not been a contender in any CBUB matches.