Saïx (spelled Saix in Japanese media), the Luna Diviner (月に舞う魔人 Tsuki ni Mau Majin?, lit. Demon Dancing in the Moon), is the Nobody of Isa, Rank VII within Organization XIII, as well as the second-in-command to Xemnas and a major antagonist in Kingdom Hearts II, Kingdom Hearts II Final Mix and Kingdom Hearts 358/2 Days. He derives power from the Moon, and uses this power to enter a berserk rage where he mercilessly attacks opponents with his massive claymore. He commands the Berserker Nobodies.
Like his master, Xemnas, Saix does not appear in the Pooh's Adventures Series in person. Rather, he and the other Kingdom Hearts villains stay in the background, manipulating Bowser and Mistress 9 through false memories of so-called "relationships" to Dark Specter and Queen Beryl.
However, Saix does appear in the Sora's Adventures Series, having been sent by Master Xehanort to help aid the imbecilic man-child Ralphscoe and his recruited hired help from Bowser's league of evil. He will first appear in Sora meets Peter Pan, where he will manipulate Captain Hook into opening the keyhole to Neverland.