Amon

Amon, or Noatak, was the charismatic and mysterious leader of a group of chi blockers known as the Equalists, whose ultimate goal was to create equality for all by ridding the world of benders. A nimble and stealthy fighter, he was fearless in facing his opponents, regardless of their bending skills and abilities.
Claiming he was a non-bender, Amon possessed the unique ability to remove a person's bending permanently, something which only the Avatar is said to have. While complete conquest of Republic City by the Equalists was at hand, Amon was revealed by Avatar Korra to be a fraud, in actuality a prodigious Northern Water Tribe bloodbender named Noatok related to past crime boss Yakone and former-Chairman Tarrlok.

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(c) Legend of Korra.