Jensen Ackles went out for the role of Captain America. And while I think it's great that Chris Evans got the job, I think it's a shame that Ackles doesn't even get SOME place in the universe he actually went for. So, personally, I think that another great choice, would be for him to play Marvel's superhero Robert Reynolds, aka The Sentry.
He's awesome, he can act, and women already find him incredibly attractive now. Imagine him with shoulder-length hair (or...ya know, google the pics to judge for yourself)
Point is, he could make a good psychologically-tormented superhuman, with frightening unimaginable power and potentially a connection to the divine (sound familiar? HELLO, SUPERNATURAL). And that is all the heck there is to say on the matter. >:(
“…Judge not what a man has done, but judge what he could have done if he was a different bloke altogether. For art thou a leper? And a leper can changeth his spots…” --Rudy Wade, Misfits (Series 4, Episode 8)