Roh Kar was a Martian lawman who traveled to Earth to apprehend a Martian criminal, who had fled the planet after stealing an invisibility belt. Soon after his own arrival on Earth, Roh Kar met the Batman and Robin. Already familiar with the Caped Crusader's reputation as a lawman on Earth, from the observations he and his fellow Martians had made of the people of Earth in general and the Batman in particular, Roh Kar gladly accepted the Dynamic Duo's help in pursuing and capturing the alien criminal.
- Martian Physiology: The average Martian possesses the potential for the following power set:
- Shape-Shifting: Martians have psionic control of their physical for down to the molecular level. This allows them to a form of shape-shifting that allows them to mimic other forms, elongate aspects of their body, increase or decrease their physical size, and so on.
- Invisibility: Martians can cause the biopolymers in their bodies to lose their ability to reflect light, making the Martians invisible to normal light and human sight.
- Phasing: Martians can go through solid matter.
- Superhuman Durability
- Superhuman Strength
- Superhuman Stamina
- Extrasensory Input
- Super Hearing
- Martian Vision: Martian visual acuity greatly exceed human norms and allows for a wider range of information to be observed. This includes the following:
- Telepathy: Martians have the ability to read the minds of others and project their thoughts to varying degrees. They can also project their mental essences into a gestalt community known as the "Great Mind". Through this, the community can enhance the telepathic strength of other Martians. This power can also enable them to reverse the effects of amnesia or psychological brainwashing. 
- Astral Projection
- Mind Control: As an extension of this, Martians can also use the ability to alter a psychological profile of a target, enabling them to manipulate, and in some cases, outright control that individual. This practice is greatly discouraged however, and only rarely used. 
- Telepathic Relay
- Telepathic Assault
- Oxygen: Earth's atmosphere and the oxygen present in it, made Roh "dizzy". This problem was easily controlled by breathing lightly.
- Vulnerability to Fire: Martians are much more vulnerable to fire than the average Earth human. At times this has been portrayed as physical, psychological, or a combination of the two. The effect of this is to strip any Martian of their powers as they involuntarily lose control of their body.
- This version of Roh Kar, including all history and corresponding appearances, was erased from existence following the collapse of the original Multiverse in the 1985–86 Crisis on Infinite Earths limited series. Even though versions of the character may have since appeared, this information does not apply to those versions.
- This character was introduced as "The Manhunter from Mars", which probably served as the inspiration for the Martian Manhunter introduced two years later, or maybe it was just a true coincidence.
- 1 Appearances of Roh Kar (Earth-Two)
- 1 Images featuring Roh Kar (Earth-Two)
- Quotations by or about Roh Kar (Earth-Two)
- Character Gallery: Roh Kar (Earth-Two)