Mega Man X is the protagonist of the Mega Man X series, and a side character in the Zero series. He was created by the robotics scientist, Dr. Thomas Light, in the twilight years of his life. X is a remarkable robot with many of the same features and characteristics as the original Mega Man, though he possesses something that not even the original had: the will of a free-thinking human being, coupled with limitless evolutionary potential. He is incredibly advanced for this reason, but also incredibly dangerous. It was for this reason that Dr. Light sealed X away in a capsule after he finished creating X, running him through a test in cyberspace to train his moral compass. Sadly, the process would allow X to outlive Light. He would reawaken 100 years into the future to another robotics scientist named Dr. Cain. Together with Cain, he would become the foundation for a new race of robotic organisms known as Reploids.

In the Zero series, X now takes the form of a miniature being known as a Cyber Elf. This form was taken after sealing himself away in an attempt to halt his own creation gone rogue: The Mother Elf, reclassified as the Dark Elf. He now appears to Zero as a spirit, essentially, and aids him wherever necessary.

X as a character is incredibly pacifistic and introspective. He hates thoughts and actions pertaining to violence, especially when it comes to his own kin, the Reploids; however, he hates the injustice and cruelty they choose to bring far more. It is for this reason that he chooses to fight himself, for a better future and a world where humans and Reploids can live as equals. In this way, X can also be considered an idealist. In this dub, X is characterized by that same sense of justice and belief in the betterment of man and machine that has pushed him forward. That said, after this last battle, X is at his breaking point, and desperate to hold on to the only person he has left to help anchor him in his beliefs. The attempt is in vain, and X eventually gives in to despair.