X, the Xilien Controller, played by Kazuki Kitamura, is a character in the film Godzilla: Final Wars.
When the Xiliens are exposed, the Xiliens' Controller, who called himself X during an interview on a radio show, kills his superior to assume command, revealing the plan to use humans as a food source while taking control of all the mutants except for Ozaki through a property in their DNA known as "M-base". X also has the monsters placed under his control through M-base in their DNA and awakens Gigan to wipe out the EDF. The group escapes although Gigan pursues them. Gordon convinces them to travel to Antarctica to release Godzilla, which is immune to Xilien control thanks to his lack of M-base and easily destroys Gigan. The Gotengo then guides Godzilla into battle with the other monsters and returns to Tokyo to engage the Xiliens. After penetrating the mothership, the group is captured and brought before X as he summons Gorath to Earth. Though Godzilla destroys Gorath just before it crashes, it unleashes Monster X and the two monsters' battle. An upgraded Gigan joins Monster X but is intercepted by Mothra, who is gravely wounded while managing to destroy the cyborg. In the Xilien ship, X reveals that both he and Ozaki are superior beings known as "Keizers", powerful beings distinct from regular mutants born on rare occasions when human DNA and M-base are combined, before directly taking control of Ozaki to turn him against the group. A fight breaks out, and X loses control of Ozaki due to the Shobijins' blessing. X is fatally wounded, but he triggers the ship's self-destruct as the group falls back to the Gotengo moments before the mothership explodes. Godzilla and Monster X continue their battle, but X transfers his Keizer energy to Monster X before dying, enabling Monster X to transform into its final form, Keizer Ghidorah. Godzilla is nearly killed by Keizer Ghidorah, but Ozaki manages to provide him with some of his own Keizer energy, giving him the strength to emerge victorious.