Kryptonite first appeared in The Adventures of Superman episode “The Meteor from Krypton”. As usual, the green rock would rob Superman of his powers and cause him great pain, leaving him incapacitated ...
Superman is able to stop the meteor, but it breaks up and showers the Earth in Kryptonite. Superman Unlimited #1’s cover boasts that this is the beginning of the Emerald Age, and things change rapidly ...
Kryptonite has long been Batman's primary means of taking on Superman, but we've never seen him go to such an extreme in DC's brutal new crossover.