Z

Z is the identity of an unknown individual who was a former agent going on covert missions for the government, and the main antagonist of X2 and hidden secondary antagonist of X3. After his wife is killed, apparently by X|Theo Edwin, he uses his skills to become a villain and exact revenge on Theo.

After hearing about Theo's vigilante acts, who is going under the name "X", Z decides to go to Central City himself. Confronting X twice, he proved to be more than a match for X. Eventually, Z is defeated by X and incarcerated, however unknown to X, he is later broken out by Chronos. It is revealed that Chronos had traveled back in time and killed Z's wife and framed X, in order to get Z to kill him.

After one last fight, Z and X arrive to the date where Z's wife dies by Chronos, where X manages to stop Chronos from murdering her. After thanking X for what he's done, Z disappears due to his past being altered where he does not become a villain.