The barbarian invasions were the responsible for the end of the Western Roman Empire, while the Eastern Roman Empire, later transformed into the Byzantine Empire, lasted longer, the Western Roman Empire fell under the barbaric invasions.
These invasions lasted hundreds of years but officially historians say that the end of the Western Roman Empire was on the year of 476 CE when Romulus Augustulus was deposed by Germanic rulers.
Besides the fall of the Empire, the Roman Empire was very much affected by the Germanics because they changed military, political and social aspects of Roman society.