Who are the characters who don't need to breathe?
It seems that some characters, like Juggernaut or Colossus, need or don't need to depending on who is writing and what is convenient for the story.
So who has been shown, at least in some comics, to be able to survive without breathing at all.
(let's get the cosmic entities, the Heralds and the robots out of the way)
Blue Marvel
Colossus
Diamondhead
Juggernaut
Mercury
I'm not sure about the gods. I believe Thor can hold his breath for a long time, but he actually need to breathe, right?