Romulus Augustulus was the last Emperor of the Western Roman Empire, even though he was a puppet emperor. he died 476 AD
He was deposed in 476 he died later, the point were most consider the end of the Roman emperors is Heraclius (sp?) but all emperors called themselves roman so it doesnt matter if the west existed or not, the roman empire existed aslong as there was an emperor there to rule it and in 1453 that ended.

I think personally the Holy roman empire was simply a joke lol