What are Transformers?

Transformers are fictional, sentient alien robots and the title characters of a popular Hasbro toy line and its spin-offs. Coming from the planet Cybertron, the Transformers are divided into two factions, the heroic Autobots, led by Optimus Prime, and the evil Decepticons, almost always led by Megatron. They are able to "transform", rearranging their bodies into common or innocuous forms, including vehicles (the most commonly known form), devices or animals. They can displace mass (i.e. shrink and expand), combine with one another, and apply synthetic flesh.