True Organization XIII

The True Organization XIII (also known as the Seekers of Darkness) are, alongside Maleficent and her Legion of Darkness, the main antagonists of the Dark Seeker Saga of Kingdom Hearts, as well as of J. Tom's Kingdom Hearts series.

Chosen

 * I: Master Xehanort (the original Xehanort)
 * II: Ansem, Seeker of Darkness (Terra-Xehanort's Heartless)
 * III: Xemnas (Terra-Xehanort's Nobody)
 * IV: Xigbar (Luxu's Nobody)
 * V: Luxord
 * VI: Larxene (Elrena's Nobody)
 * VII: Marluxia (Lauriam's Nobody)
 * VIII: Sephiroth (Cloud's Darkness; originally a reserve, he joined the Organization after Isa was restored)
 * IX: Terra-Xehanort Replica (Exactly What It Says On The Tin: a Replica of Terra-Xehanort; replaced the original Terra-Xehanort after Terra was freed from Xehanort's clutches)
 * X: Dark Riku (a combination of Riku from when he was possessed by Ansem, Seeker of Darkness, and Riku Replica from when he thought he was the real Riku)
 * XI: Vanitas (Ven's Darkness; implied to be one of the 13 beings of pure darkness created by the first Keyblade War)
 * XII: Young Xehanort (Master Xehanort's time travelling past self)
 * XIII: Sora's Heartless (Xehanort wanted Sora to be one of his Seekers of Darkness; since Sora's Nobody, Roxas, Sora's imperfect female clone, Xion, and Sora himself being Guardians of Light, Sora's Heartless was Xehanort's only other choice)

Removed

 * Demyx (was benched; restored as Myde by accident by Young Xehanort; defected for the Guardians of Light afterwards)
 * Saix (the original number VIII; restored to Isa by Oswald the Lucky Rabbit; defected for the Guardians of Light afterwards; replaced by Sephiroth)
 * Terra-Xehanort (the original number IX; Xehanort was expelled from Terra's body)