The Autobots are usually featured as the main protagonists in the Transformers multimedia franchise, and are depicted in a collection of various toys, cartoons, films, graphic novels, and paperback books first introduced in 1984. The Autobots are living robots from the planet Cybertron who, like most Transformers, are each imbued with a unique "life force" known as a "spark." Led by Optimus Prime in most stories, the Autobots believe "freedom is the right of all sentient life" and are often engaged in a civil war with the Decepticons, a faction of transformers dedicated to military conquest and usually headed by Megatron. In a mirror universe portrayed in Transformers: Shattered Glass, the Autobots are villains opposed by the heroic Decepticons.