Federation Special Operator John Harrisson, as seen in the movie with his big "Boolean Phaser Gun" in Section 31 Uniform. John Harrisson was a longer time a Special Operator of Section 31 under the command of Alexander Marcus. But this name was only a smokescreen to hide his true Identity - Khan, Noonien Singh.
The other Kreon Figures named as "Specialists" are to complete the crew of the U.S.S. Vengeance. Wich "Specialist Captain" Alexander Marcus is.