Xemnas (ゼムナス, Zemunasu?) is the Nobody of Xehanort, he is also known as "The Superior of the In-Between" (狭間の指導者, Hazama no Shidōsha?). The character's name is based on Xehanort's alias, "Ansem". Xemnas is the leader of the Organization and the primary villain of Kingdom Hearts II. He controls Sorcerer Nobodies, and fights with Ethereal Blades called "Interdiction" (フォービドゥン, Fōbidun?, lit. "Forbidden"). The character can manipulate nothingness to phase through solid matter and manifest energy-based shields and projectiles.[7] The character first appeared in Kingdom Hearts Final Mix as an optional boss labeled "Unknown" (謎の男, Nazo no Otoko?, lit. "Enigmatic Man"). During their first meeting at Hollow Bastion, Xemnas tests Sora to glance into his memories to use them to create Xion as a back-up plan, in case Sora is unable to be useful in the Organization's plans; later, he decides to use her to not only kill off Roxas, but also ensure Sora remains asleep. Other than his agenda of becoming one with Kingdom Hearts to transcend into a higher state of being, Xemnas has another goal: to reach the Chamber of Wakening for reasons none of the other Organization members know, hinting that he possesses his original self's obsession with regaining his full memory. Xemnas is voiced by Norio Wakamoto and Paul St. Peter in Japanese and English respectively.[11]

In "Kingdom Hearts II", Xemnas initially appears in Roxas's dream recollection of meeting him on his sixth day as an Organization member.[1] Xemnas also makes two appearances at Hollow Bastion; in the second, his identity is clarified and his face is revealed. His plan is to increase the power of Kingdom Hearts by having Sora destroy Heartless, releasing the hearts inside them. At the World That Never Was, Xemnas was waiting for the completion of Kingdom Hearts until Ansem the Wise attempts to digitally contain its power. However, Ansem's machine overloads and explodes, apparently killing him and damaging Kingdom Hearts. After Sora refuses to aid him in restoring Kingdom Hearts, Xemnas uses what is left of Kingdom Hearts' power to take on a new form to fight Sora's party. Though Xemnas is thought to be defeated, he separates Sora and Riku from the others to attack them. However, the two defeat Xemnas and he fades into darkness. He is also the only member of the Organization to appear in Kingdom Hearts Final Mix.[12]