NOAD describes a figurehead as

a nominal leader or head without real power.

I'm wondering if there's a complimentary one-word term for the person who does wield the power in such a situation. I'm aware of the phrase, power behind the throne,

a person or organization that exerts authority or influence without having formal status.

I'm just hoping there's a way to refer to such a person more directly and succinctly.

NOAD describes a figurehead as

a nominal leader or head without real power.

I'm wondering if there's a complementary one-word term for the person who does wield the power in such a situation. I'm aware of the phrase, power behind the throne,

a person or organization that exerts authority or influence without having formal status.

I'm just hoping there's a way to refer to such a person more directly and succinctly.