Matter-Eater Lad

The name says it all doesn't it? This one literally gives definition to the term 'iron stomach' as the lad can literally eat all or any form of matter. A little history to his power mystery—he hails from the planet Bismoll (referencing the  tummy medicine Pepto-bismoll perhaps?) where certain poisonous microbes have made all food indelible. As such, he and all the other inhabitants of this planet evolve to have this ability which makes us wonder why there aren't more of his kind flying around being all..well..super. 

Incidentally, he is also thought to be able to eat right through matter that would otherwise be considered indestructible. This would technically mean that he could destroy all the other heroes out there simply by—you guessed it—eating them!