Cybertron is a fictional planet, the homeworld of the Transformers in the various fictional incarnations of the metaseries and toyline by Hasbro. In the Japanese series, the planet is referred to as "Cybertron" (first shown on Japanese Galaxy Force packaging, despite the fact that "Cybertron" is the Japanese name for "Autobot") pronounced as セイバートロン Seibātoron. Cybertron is populated by mechanical life forms of variable size who can transform into all kinds of machinery. These are called Cybertronians, or Transformers.
Read more about Cybertron: Beast Era, Unicron Trilogy, Transformers Animated, Animated Series