Master Xehanort (voiced by the late Leonard Nimoy) is the main antagonist of the Kingdom Hearts games. He is a Keyblade Master who was obsessed with the legendary Keyblade War. Master Xehanort once tried to teach Ventus to control the darkness, but it was too much for the boy, so he used his Keyblade to split his heart in two, bringing out a separate personality, & controlling the darkness, dubbing him Vanitas. Then Xehanort left Ventus in the care of Master Eraqus, so that Ventus would become strong enough for his ultimate plan: to create a χ-blade to create another Keyblade War and acquire the true Kingdom Hearts. After a series of events that he started, Master Xehanort unlocked his heart and forced it into a younger Keyblade wielder named Terra, and thus, Terra-Xehanort was born.
After Master Xehanort took Terra's body, Terra-Xehanort (voiced by Richard Epcar) fought his armor, and later on Aqua, only to be defeated twice. During the internal conflict of hearts within him, Terra-Xehanort stabbed himself with his Keyblade to force Terra out, but the results ended up with him falling into the Realm of Darkness, and lost all his memories. He was saved by Aqua, and became the apprentice of Ansem the Wise. However he continued to battle Terra inside the new Xehanort's body.
In Jeffrey, Jaden & Friends' Storm Adventures of Kingdom Hearts: Dream Drop Distance, Xehanort's younger self traveled through time to the future (a power given to him from Ansem the Seeker of Darkness) to gather 13 vessel's of Xehanort's heart and attempted to make Sora become the 13th vessel.
- Master Xehanort is one of the ultimate enemies in the Jaden's Adventures series and the Jeffrey & Friends' Adventures series.
- It is revealed that Master Xehanort is the one who gave the Yubel card Jaden once owned the dark energy to make her come to life, thus starting the events that took place in Yu-Gi-Oh! GX Season 3.
- Master Xehanort will be Darkblade's long time nemesis.
- Master Xehanort will become Hiccup's enemy in the future.
- In the Thunderbolts Adventure Series, Courtney wants to get her revenge on him and Vanitas for getting rid of her adoptive family.