Vanitas is a Keyblade wielder and the secondary antagonist of Kingdom Hearts Birth By Sleep.
He was created when Master Xehanort split Ventus’s heart into two pieces: one of pure light and one of pure darkness. While Ventus was sent away to the Land of Departure, Vanitas trained with Xehanort to become an equally powerful force to merge with Ventus to forge the X-Blade. During that time, Vanitas discovered that his negative emotions took physical form as beings called the Unversed. Xehanort takes notice of this development and uses Vanitas to send the Unversed into different worlds so that Ventus could get stronger and to make Terra into an ideal vessel. After successfully goading Ventus into following Terra and stringing along Aqua and Terra using the Unversed as part of Xehanort’s plan, Vanitas clashes with Ventus at the Keyblade Graveyard, resulting in the two merging and forging the X-blade. Though Vanitas manages to posess Ventus’ body, he is defeated by Ventus in the Dive to the Heart resulting in the destruction of the X-blade and Ventus’ heart being damaged for good.
Although he was defeated in Birth By Sleep, Vanitas makes a brief appearance in Dream Drop Distance as a result of Young Xehanort travelling through time seeking different versions of himself.
Vanitas truly returns in Kingdom Hearts III, now sporting a black coat and as a member of the real Organization XIII.
