People who may or may not actually exist

John Baez assigns probabilities.

The only estimate I think is outright dumb is the one for Osama bin Laden, at 98% certainty of existence. I think it has to be 99.9% or much higher, given all the photos, the widely-published identities of family members, etc. I love a conspiracy theory as much as the next person, but who would be willing to bet, even at 50 to 1, that there is no such person as Osama bin Laden? Note that if he's dead, he still counts as (having been) a real person.