Original robot created by Dr. Thomas Light and is the template of all the reploids. Joined the Maverick/Irregular Hunters due to being partially responsible in designing the reploids who went maverick. He was set to sleep in a capsule after his creation in Dr. Light secret Laboratory. Centuries later, he was discovered by Dr.Cain, who was himself a great scientist and who was the one to create the reploid generation using X (name by which he is referred in the game and the serie) as background, but all even so, there was one thing which makes X unique to other reploids, which is his ability to have feelings and choose his own way, but it is at the same time his main weakness.