Recusant's Sigil

"As your flesh bears the sigil, so your name shall be known as that...of a recusant."

—Xemnas to Sora, at the beginning of their battle.

The Recusant's Sigil (異端の印, Itan no shirushi, lit. "Mark of heresy") is a symbol created by Xehanort to represent a Nobody's rejection of his or her human form. Each of the members of the original Organization XIII had names that bore the Recusant's Sigil; the symbol itself is derived from Xehanort's sleeping memories of the χ-blade.

In order to track his movements in the Sleeping Worlds, Xehanort marked Sora with the Recusant's Sigil by placing a silver "X" on his shirt.