Detective Comics #273 (November, 1959)

"Gasps of astonishment go up," as city citizens gazed upon an unearthly missile overhead. "The strange craft lands in a nearby park," from which a jaundiced extraterrestrial exited. A crowd gathered nearby, taking cover behind a statue. "Is he friendly-- or dangerous? Approach him carefully!" Caution proved the better part of valor, as the yellow-skinned Martian drew a ray gun that vaporized the statue with one shot. "Out of my way, Earth people!" As the humans evacuated the scene, B'rett thought to himself, "Ha, ha... Look at them flee! With my Martian powers, I'll become the most powerful man on Earth!"

"Immediately, the alien newcomer begins his reign of crime..." Recognizing Earth people stored their money in banks, B'rett used "one of my Martian talents" to pass immaterially through a vault wall to help himself. Confronted by armed guards, he chided, "Guns? You think you can stop me with your puny guns? Come to think of it, who needs money? I can take anything I want from you helpless Earthlings!"

Minutes later, Captain Harding summoned ace Detective John Jones to his office. "Jones... Hundreds of calls are pouring in about an alien on Earth!" Jones promised to look into it, while wondering "what the chief would say if he knew that I'm an alien... Still, I doubt there's actually another outer-spaceman on Earth!" However, Detective Jones soon found himself in a crowd watching B'rett plow through heavy traffic with his super-breath. "Great Suns-- It's true!" The super-sleuth noticed B'rett was warning people not to follow him, rather than simply turning invisible, "as any Martian can do." Only through his Martian Eyesight could Jones follow the evil alien's sudden burst of speed, leading to an abandoned warehouse. Jones followed B'rett into the warehouse before undergoing his "startling change" into J'onn J'onzz, the Manhunter from Mars. B'rett exclaimed "Thundering Meteors-- another Martian! How did you get here?" J'onzz played it tough, demanding "Suppose you first tell me who you are-- and how you got here?"

"My name is B'rett! I-- er-- had to leave Mars in a hurry... so I hid myself in an experimental missile that overshot its mark-- and accidentally landed on Earth!" The Martian Manhunter wasn't buying it. "A criminal, eh? Well-- I'm returning you to your missile!" B'rett was no more interested in J'onn's line, and drew his Martian ray gun. "I may be invulnerable to Earth weapons-- but that gadget can finish me for good!" The Alien Atlas turned himself invisible as the Martian Criminal used up his gun's battery firing blind. B'rett had "plenty more" batteries at the missile. "Meanwhile, I've got another weapon I can use against you!" The Martian Marvel was shocked at the sight of "A pellet of Formula Z6-- the chemical given to Martian criminals to rob them of their super-powers while invisible! No wonder you never vanish!" J'onn J'onzz collapsed from exposure to the gas, though he remained obscured. "Exactly... and from now on, you will never be able to use your Martian powers while invisible, either!"

B'rett had escaped to his missile by the time J'onzz regained consciousness and resumed the chase. As B'rett exited the craft with his re-charged ray gun, he was met by three police officers in over their heads. "I can't use my powers to save them, unless I become visible-- and give away my presence on Earth! ...I have no choice..." The police were rattled by the sudden appearance of two Martians, but the Sleuth from Outer Space assured, "...have no fear of me! I am on Earth to fight crime!" B'rett dismissed, "BAH! ...Take one more step, Manhunter, and I'll start blasting!" J'onzz knew "he means it," and used his Martian Distance Vision to detect a man burning leaves miles away. The Manhunter filled his Martian lungs, then let loose a mighty blast that drew in the burning leaves and encircled B'rett. "Fire-- the one Martian weakness! I-- I'm losing all my strength! Oh-h-h!" J'onzz announced, "Now's your chance, officers... Grab him! I don't dare come any closer to that fire!"

"Helpless, the evil Martian is placed back in his missile-- and soon after, at a nearby rocket launching base," he was shot into orbit around Mars at the Manhunter's request, "So the Martians will then be able to send up a ship and bring it down." Just after liftoff, the familiar voice of Captain Harding greeted the once-Secret Visitor from Mars. As he shook J'onzz's hand, Harding considered, "Imagine... a Martian Manhunter, here on Earth! Would I love to have you on the force!" Though he was intent on continuing to keep his Earth identity secret from even the chief, J'onzz promised "I will always be available for emergencies." Later at headquarters, Harding continued to brag to "Jones-- until today, you were the top detective in town... but from now on, you'll have to take second place to the Manhunter from Mars!"

“The Unmasking of J'onn J'onzz” by Jack Miller and Joe Certa.