Board Thread:General Discussion/@comment-7669924-20151018030852/@comment-7064521-20151018230753

Blademaster Jauffre wrote: Wait, if only the Dragonborn (or another Dragon) can kill a dragon, then what happened to Nafalilargus?

Nafalilargus didn't truly die. It is unknown if Alduin revived him, but it's likely the World-Eater did not bring the Septim's dragon back.