X

X may refer to:
 * Mega Man X, the main protagonist of the Mega Man X series. In the Mega Man Zero series, he is the true leader of Neo Arcadia, known as Original X to distinguish from Copy X. Additionally, information on his appearance in the Archie Comics Mega Man series can be found on Mega Man X (character)/Archie Comics.
 * Copy X, the main antagonist of Mega Man Zero. He is a copy of the Original X designed and built by Ciel to supposedly be a perfect copy of the original, and the Neo Arcadia leader in the Mega Man Zero series timeline, taking over Original X's rules.
 * Model X, a Biometal created by Ciel.
 * GX, an evil copy of X from Rockman X Mega Mission who is also known under just "X" or "Return X".
 * Mr. X, an antagonist in Mega Man 6.