Unicron

Unicron is the closest thing the G1 cartoon has to a devil: a planet-sized machine that eats worlds, and the only antagonist ever presented as being genuinely beyond Megatron's league. He is introduced in the opening minutes of The Transformers: The Movie consuming the peaceful world of Lithone whole, an act of casual annihilation staged specifically to establish that everything the Autobots and Decepticons have been fighting over is trivial by comparison. He does not scheme in the way Megatron schemes; he simply advances, and negotiates only when it saves him effort.

His method is transactional. Drifting past the wreckage of the Battle of Autobot City, he hacks Autobot City's infirmary cameras, watches Optimus Prime hand the Matrix of Leadership to Ultra Magnus, and identifies the Matrix as the one thing in creation that can kill him. He then scoops up the dying Decepticons jettisoned from Astrotrain and offers their broken leader a bargain: a new body and new troops in exchange for destroying the Matrix. Megatron becomes Galvatron; Thundercracker, Skywarp and the rest become Scourge, Cyclonus and the Sweeps. When Galvatron proves insolent, Unicron does not argue; he inflicts agony until Galvatron kneels, then swallows the planet Cybertron's defenders and transforms into a colossal robot to tear Cybertron apart himself.

What makes him memorable is tone. Orson Welles' bored, sepulchral delivery gives Unicron the register of an irritated god rather than a villain, and lines like "For a time, I considered sparing your wretched little planet Cybertron. But now you shall witness its dismemberment!" land as sentencing rather than threat. He is finally killed from the inside when Hot Rod, now Rodimus Prime, opens the Matrix within his throat. Even then he refuses to stay dead: his severed head takes orbit around Cybertron and remains a lurking presence through season three.

Planet-mode consumption: Unicron can open his equatorial maw and devour entire worlds, as he does to Lithone, and transform into a titanic robot to dismantle planets by hand. He rebuilds other Transformers entirely, converting dying Decepticons into Galvatron, Cyclonus, Scourge and the Sweeps, and can inflict crippling pain on those he has remade as a means of enforcing obedience. He operates across interstellar distances, hacks remote systems (Autobot City's infirmary cameras), projects his voice and image into the minds of his servants, and repairs himself. His documented weaknesses are precise: the Matrix of Leadership, whose energies destroy him from within when opened inside his body, and a certain arrogance that leads him to fight in robot mode rather than simply consuming his enemies. In season three his surviving head is dependent on outside help for optics, a transformation cog and a body, and is vulnerable to internal sabotage.

• Galvatron: his creation and unwilling servant, rebuilt from the dying Megatron and kept in line through inflicted agony rather than loyalty.
• Cyclonus and Scourge: fashioned from the jettisoned bodies of Skywarp, Thundercracker and other broken Decepticons as Galvatron's new officer corps.
• The Matrix of Leadership and its bearers: Optimus Prime, Ultra Magnus and finally Rodimus Prime represent the single thing in existence he fears.
• Starscream's ghost: the disembodied Seeker revives Unicron's head in season three, the only being to ever get the better of him in a bargain, briefly.

The Marvel version is a fundamentally different creature. Where the cartoon offers a machine built by Primacron, Marvel (chiefly through Simon Furman) makes Unicron a god: the Chaos Bringer, dark twin of the creator-deity Primus, whose own body is the planet Cybertron. Marvel's Unicron is driven by an ancient supernatural feud rather than appetite alone, and he summons the Transformers of Earth to Cybertron for a final confrontation in which Primus speaks through the body of Emirate Xaaron. His death is also different: rather than being killed by Rodimus Prime, he is worn down by the massed Transformers, briefly disoriented by the human Neo-Knight Rapture, wounded by Circuit Breaker's electrical attacks, and finally destroyed when Optimus Prime flies into his maw and opens the Creation Matrix. Marvel also gives him a serious pre-history as an ongoing cosmic threat rather than a one-film antagonist, and it is Marvel's mythology, not the cartoon's, that later franchises adopted wholesale.

In the cartoon he is destroyed in 2005 when Hot Rod, transformed into Rodimus Prime, opens the Matrix of Leadership inside his body; the explosion scatters his remains and leaves his severed head in orbit around Cybertron as a grim new moon. That head is reactivated by Starscream's ghost in "Five Faces of Darkness" and pursues a plan to claim Cybertron as a replacement body, which fails; by "Ghost in the Machine" the barely-conscious head is finally shut down when Grimlock and the newly built Technobots disable its internal mechanisms, with Strafe severing the critical connections. In Marvel he is instead destroyed by Optimus Prime opening the Creation Matrix inside him during the assault on Cybertron.

• Unicron was voiced by Orson Welles in what became the last performance of his career; he recorded shortly before his death in October 1985 and the finished track was electronically processed for the film.
• His design, along with the rest of the movie's new characters, came from Floro Dery, and his transformation between planet and robot modes was among the most expensive animation in the film.
• No Generation 1 Unicron toy was ever released. The character went untoyed for seventeen years until the enormous Armada Unicron figure in 2003, which is why the cartoon design had no toy-accuracy constraints.
• Unicron's scale is wildly inconsistent across the movie, appearing anywhere from moon-sized to larger than Cybertron itself depending on the shot.
• "Call of the Primitives" was written long before the Marvel comics invented the Primus/Unicron creation myth, which is why the cartoon's Primacron origin flatly contradicts the mythology that later continuities treat as canon.

Where the cartoon, the Marvel comics and the toy bios disagree, or where a popular claim does not hold up. We record these rather than smoothing them over.

• Origin: the cartoon's "Call of the Primitives" makes him a robot built by Primacron; Marvel makes him a primordial god and twin of Primus. These cannot be reconciled, and every later continuity follows Marvel.
• Manner of death: killed by Rodimus Prime and the Matrix in the movie, versus killed by Optimus Prime and the Creation Matrix in Marvel.
• Nature of his servants: the cartoon shows him rebuilding specific dead Decepticons into Galvatron, Cyclonus and Scourge; Marvel's Unicron creates his heralds by different means and the identity mapping of the movie bodies is never settled on screen.