What about Dhurnevir (sp)?
Technically he is not completely dead, because his soul is in the soul cairn due to a bargain with the ideal masters you really can't use him as an example. CAR105 3
Those dragonborn emperors were generally not born with the soul of a dragon. Lore wise those who were born with the soul of a dragon would have had that dragon's soul reclaimed by Akatosh, the Septim dynasty was referred to as dragonborn emperors because of Mother effin Hjalti Early-Beard Ysmir Tiber Talos Stormcrown Septim, yes he has a long ass name.