http://www.bethblog.com/index.php/2011/09/27/a-star-studded-cast/ As seen on this list of voice actors theres a mention of an ancient group of warriors who killed the dragons already. I cant remember where but i also saw a mention of a warrior ghost whos going to help us defeat Alduiin like he did in his time.

I dont know if this is old news but i thought it was an interesting tidbit of knowledge.