Transformers are fictional alien robots and the titular characters of a popular Hasbro toy line and its spin-offs. They come from the planet Cybertron and are divided into the heroic Autobots, led by Optimus Prime, and the evil Decepticons, led by Megatron. They are able to "transform", rearranging their bodies into common or innocuous forms, including vehicles, devices or animals. Beyond that, they can displace mass (i.e. shrink and expand), combine with one another, and apply synthetic flesh (see: Transformers technology). This ability to transform is reflected in the programs' taglines "More Than Meets the Eye" and "Robots in Disguise". All Transformers stories and characters, in a range of media, have been based around this core concept since their debut in 1984.