The title of the "Last Roman Emperor" typically refers to Romulus Augustulus, who ruled from 475 to 476 AD. He was a young emperor, placed on the throne by his father, who was a general. His reign marked the end of the Western Roman Empire, which had been in decline for several centuries due to internal strife and external invasions.
In 476 AD, Odoacer, a Germanic chieftain, deposed Romulus Augustulus, effectively ending the Western Roman Empire. This event is often considered the fall of Rome, leading to the rise of various barbarian kingdoms in Europe. The Eastern Roman Empire, known as the Byzantine Empire, continued to exist for nearly another thousand years.