Master Manipulators are a specific type of Mastermind, a highly intelligent adversary who often does not engage in direct conflict with a hero or rival villain unless they feel they have no choice or have already "won". They excel at driving wedges between former allies, breaking friendships, or even just causing unrest via manipulating the nature of society, individuals, or the system. Many of them are capable of causing mass disruption and toppling entire civilizations before they are even seen as suspects and are often seen as heroes or "harmless" individuals. Thus, they are among the most dangerous of villains, especially when combined with psychopathic tendencies.
Good examples include false heroes who convince others to fight for them, only to reveal in time that these fights were just for their own benefits, or rulers to usurp vast power and resources via having rival factions war with one another rather than against them. Palpatine, David Xanatos and some versions of Lex Luthor are examples of this, as would some versions of the Joker and the Riddler. However, do not add this to con-artists or simply "traitorous" individuals. This is for characters who excel at tricking others in-universe to either serve their cause or ignore their true threat until it is too late.
A Master Manipulator is often so good at having others fight and bicker or lacing their setting with discord that even when exposed, they can still amass a following of supporters or fall back on alternative plans, like any good mastermind.