Creation
Roh Kar was created by Edmond Hamilton and Lew Schwartz and is considered the prototype for John Jones, Manhunter From Mars. Roh Kar made a single appearance in Batman #78 (two years prior to the introduction of J’onn J’onzz). The Golden Age Roh Kar is no longer considered part of modern continuity.
Story Arc
Roh Kar, a lawman of Mars, came to Earth in search of a criminal named Quork. After landing on the planet he came into contact with Batman and Robin, who were also tracking down the criminal. They teamed up in order to take him down. Roh Kar took Quork into custody and returned him to Mars to face charges.
Powers
Roh Kar did no exhibit any of the powers of the Silver Age Martians (such as J’onn J’onzz) but did have access to advanced technology far beyond Earth’s.
Other versions
An homage character named Roh’Kar appeared in the 2006 Martian Manhunter mini series.