Who is the final bad guy in one piece?

Answer 1

Of course, in the time period I am speaking from, it is impossible to tell who the final bad guy would be. However, Marshall D. Teach, aka Black Beard is rising in power and reputation (both in the TV show and as the main bad guy in One Piece). While there is, at this time, no way to prove or predict, we can guess that Teach will be the last man standing in Luffy's way to becoming the new Pirate King.