Now I did some searching through the spoiler topic and the main topic and did not find anything on this, so I hope noone said it before:
Here is a quote from the spoiler translation:
Hogback: He's a General zombie who has a special kind of flesh!!! He is a man who came from the "Wano Country" in the New World!!!
Hogback: Believe or not….!! A long time ago, he was known as a legendary samurai who killed a dragon, and his story is still passed down to this day !!!
In the forth story in Oda's short story collection Wanted! entitled Monsters, a swordsman known as Ryuma slays a dragon near the end of the story.
Not only does he fit the description Hogback gave, but he is physically similar to the zombie (has the same hairstyle and similar though less fancy clothes).
I think this character could potentially be one of Oda's other characters being brought back to life in One Piece, since someone brought back post death as a Zombie really has no effect on the original story line.
Now, hope this wasn't said before. I thought this deserved its own thread because it's a large resemblance, and does not really fit into the foreshadowing thread (it's a different story) or the theory thread (it's not really a theory? well maybe). Tell me what you think those who have read Wanted!