Grand Unifying Guesses/The World Ends With You

Mr. Mew is possessed by the following

 * Joshua
 * Neku's dead BFF
 * Another Day's Eri
 * Mr. Hanekoma
 * Mew
 * The Player
 * The Nintendo DS
 * Haruhi Suzumiya
 * Shinji Ikari
 * A Time Lord
 * Which means all of these people are different regenerations of the same Time Lord.
 * Light Yagami
 * Konata
 * Kamikaze Kaitou Jeanne
 * Danny Phantom
 * Ermac
 * Geno
 * Kefka
 * Shiki
 * Giygas
 * Everyone after undergoing Instrumentality.
 * Slimer
 * A demon
 * A cat
 * The Heartless
 * Axel
 * Bedlam
 * The world's potential
 * The Cheat
 * Jesus
 * Westley
 * Rincewind
 * Trope-tan
 * Madotsuki
 * John Lennon
 * Chuckie
 * Companion Cube
 * Neko Cat!!
 * Sissel.