X (disambiguation)

X or χ (the letter "chi") may refer to:
 * Chi and the Recusant's Sigil, which are symbols represented by an X
 * The χ-blade, a legendary weapon introduced in Kingdom Hearts Birth by Sleep
 * Kingdom Hearts χ, a Kingdom Hearts game exclusive to PC browsers
 * Kingdom Hearts Unchained χ, a Kingdom Hearts game exclusive to smartphones
 * Hunter-X, a powerful enemy ship in Kingdom Hearts II
 * Luxord, number X in Organization XIII