The Time Batman Was Killed With Kryptonite!!

Well, almost...

See, Metallo has come to Gotham to rob their S.T.A.R. Labs, and we all know who is not going to put up with that nonsense!

Well, not a robot...but we'll give you a pass on that, Batman!

[Editor's note: This is the second Metallo, Roger Corbett, who did indeed have his severed head attached to a cyborg body, and not just the brain salvaged, like his brother, John.]

Batman uses that fact to kick Metallo's butt...

Until...

What?!?

[Editor's note: Metallo is stuttering because he's dying of radiation poisoning (in his still human brain) from the uranium he uses to power himself when he can't find enough kryptonite.]

During their second encounter, when Batman is getting zapped again, Corbett explain how this works:

SCIENCE!!

So, you'd think that know that he knows the score, Batman would be fully prepped, and ready for Metallo's weapon in their 3rd encounter.

Nope.

Don't worry...

...Lois Lane swings in to save him!!

Now, you'd think that this development--kryptonite radiation can be altered to harm humans--would have gotten lots more play in the pre-Crisis DC Universe. Remember, it was canon back in those days that only Kryptonians could be hurt by Green K. It was only post-Byrneboot that it was revealed that enough exposure to kryptonite could indded cause cancer in humans--which is how Luthor lost his hand.

But if Roger Corbett--who was no genius--could figure out how to make kryptonite hurt anyone, why didn't that get passed around the underworld? Why wasn't it used more against Batman, or the Justice League, or whomever? Why didn't Firestorm use "slow particle emission" kryptonite to take down villains, since he could presumably create it out of thin air? Why wasn't Dr. Alchemy using it against the Flash?!?

Missed opportunity, is all I'm saying.

From The Brave And The Bold #175 (1981)

The Morbid Mayhem of Metallo's Murder Machine

The second pre-Crisis Earth-1 Metallo was created by the secret terror organization Skull. They kidnapped the original's brother, stuck him in a similar robot body, and sent him to get revenge on Superman for brother John's death.

Well, Roger was down with the whole "kill Superman" bit, but he was far less enthusiastic about having having a forced, non-consensual brainectomy. So he concocted to plan to destroy Skull and kill the Man Of Steel!

Using an experimental teleportation ray he stole from Skull's leader, he...well, just watch:

Eewwww!!!

Uh, how does that work, exactly?

SCIENCE!!!

And just to provide secondary "eewwww":

Now, you'd think Metallo, being a super-powered robot, would, you know, just go up and beat the crap out of the Skull agents. I mean, this plan is a little bit sophisticated for him, you know?

Ah, but he was also doing this to test the device, so he could swap his Kryptonite heart for Kal-El's Kryptonian heart, simultaneously killing Superman and making himself completely unbeatable.

SPOILER ALERT: The plan failed.

From Superman #317 (1977)