The Martian who was thought to be J'onn J'onzz was the last of his kind before coming to the evil world of Earth 3. Finding peace with the villainous Crime Syndicate, J'onzz became deadly injured sometime prior to the Syndicate choosing to abandon their world once the Anti-Monitor destroyed it. J'onzz was rendered blind, missing both his eyes, and his right arm was decayed to just bone and muscle.
When Pandora was temporarily transported to Earth 3, she met J'onzz, who begged her to know if the other Syndicate members made it to the other Earth after having chosen to leave him behind, making him the last of his people yet again. The two were not able to talk long before the Martian succumbed to his injuries. 
Since he is a green martian, he probably has all the powers the Martian Manhunter also has, which includes:
- Appearances of J'onn J'onzz (Earth 3)
- Images featuring J'onn J'onzz (Earth 3)
- Quotations by or about J'onn J'onzz (Earth 3)
- Character Gallery: J'onn J'onzz (Earth 3)