Kafka: 9
Dickinson: 3
And it depends on what you mean by "Shakespeare"--
The actor existed...has a tomb and everything...
Whether or not you believe he was the one who wrote his plays (I personally don't mind saying that he did, the Authorship Question's the least interesting one to me, and unless anything definitive ever comes up, it's always going to be "Most Interesting Conspiracy Theory" vs. Just Traditionally Saying Shakespeare...and I'll take the man from Stratford. Other actors became writers, and I've yet to find one argument for Bacon, Oxford, or Marlowe that even begins to become persuasive enough for me to seriously consider caring and thinking it was someone else. Says Shakespeare on the page, to me, Shakespeare = man on the page, ergo, he's Shakespeare to me.)
But even if it was someone else...
All three of those candidates--Bacon, Oxford, and Marlowe--all are confirmed to have existed, obviously...
So Shakespeare's not really questionable the same way Homer is.
We KNOW all four of those men existed, it's just a question of who wrote the plays, and one that can't be solved barring something truly Earth-shattering, so Shakespeare it is.
By contrast, we have no tomb or signatures or any such thing for Homer...which is fine, that's to be expected. I think there probably was a Homer, in the same way I think there was probably a Jesus--and both just had their stories/sayings exaggerated a wee bit by a devoted fan following afterward. ;)