According to KeanuIsImmortal.com, there are at least two known instances of Keanu masquerading as key historical figures—Charlemagne and Paul Mounet. The resemblance is not only uncanny, but just look at the suspicious end to Charlemagne:
Aside from the striking resemblance, the account of the death of Charlemagne rise suspicion. First of all, he crowned his son just before dying (just like he knew he was going to "die") secondly his burial was rushed during cold weather this is a clear hint that they needed to bury a body to not rise any suspicion.
Watch this video. It is irrefutable proof that Keanu Reeves is immortal. From the dawn of time he came; moving silently down through the centuries, living many secret lives, struggling to reach the time of the Gathering; when the few who remain will battle to the last. No one has ever known he was among us... until now.