I can`t really think of an emo poet, but I do know a dark one that could work very well. Try Inferno by Dante Alighieri. It is part of the of his epic poem the Divine Comedy, which also includes Purgatorio and Paradiso.
On "dark", I think of H.P. Lovecraft. But he's not "emo". He's just dark.
Another name that comes to my mind is Paul Celan. Especially his "Todesfuge" (death fugue). Gives you the creeps...
"Words have no power to impress the mind without the exquisite horror of their reality." ~E.A.P~ Definitely Poe! At least, he's the most famous of the dark poets...
I'm not so sure about emo but Edgar allan poe is pretty dark!
Edgar Allan Poe was the first to spring to mind for me too!
Edgar Allen Poe is deffinetely a dark poet