The term "Generation 1" covers both the animated television series The Transformers and the comic book series of the same name, which are further divided into Japanese and British spin-offs, respectively. Sequels followed, such as the Generation 2 comic book and Beast Wars TV series, which became its own mini-universe. Generation 1 characters underwent two reboots with Dreamwave in 2001 and IDW Publishing in 2005, also as a remastered series. There have been other incarnations of the story based on different toy lines during and after the 20th-Century. The first was the Robots in Disguise series, followed by three shows (Armada, Energon, and Cybertron) that constitute a single universe called the "Unicron Trilogy". A live-action film was also released in 2007, with a sequel in 2009, a second sequel in 2011, and a third in 2014. again distinct from previous incarnations, while the Transformers: Animated series merged concepts from the G1 story-arc, the 2007 live-action film and the "Unicron Trilogy". Transformers: Prime previously aired on The Hub.
Although populated mainly with new characters, The Headmasters did continue to feature characters from all previous seasons, including new versions of Soundwave and Blaster , rebuilt after a duel that destroyed them both as Soundblaster and Twincast. Human Daniel Witwicky and his young Autobot friend Wheelie also played major roles in the series, serving as the youthful characters for the audience to identify with. More new characters continued to pour in when Galvatron returned to leadership and the Decepticons embarked on a space voyage, ransacking planets in a chain of stories that introduced the Horrorcons and Autobot and Decepticon Clones. The return to Earth was no less momentous, as the Decepticon ninja six-changer Sixshot killed Ultra Magnus, and the Autobot Headmasters finished off Galvatron. When the Decepticons then returned to Master, refugees from the planet were caught in a plasma bomb accident that fused them to the arms of several Autobots and Decepticons, creating the Targetmasters, and in a final move, Scorponok attempted the destruction of Earth, only to be foiled, thanks in part to a traitorous Sixshot.