Mega Man X, commonly known as "X", was created by Dr. Thomas Light. X was a new type of robot with the ability to think, feel, and make his own decisions. Recognizing the potential danger of this model (in particular if he were to break the first rule of robotics: a robot must never harm a human being), Light sealed X away in a diagnostic capsule for over 30 years of testing. X's capsule was uncovered by an archaeologist named Dr. Cain almost 100 years after X's creation. Excited by the possibilities X presented, Cain disregarded the warnings Light had logged in the capsule and created a legion of robots that replicated X's free will; these robots were called "Reploids" (shortened from Replica Android, but known as "Repliroids" in Japan).