Unicron

Unicron is usually filed as a character, but for a locations section he is a world with an inside. Externally he is a ringed planet the size of a gas giant that transforms into a humanoid form hundreds of miles tall, and he consumes planets by opening his face and drawing them into his maw. The 1986 film opens on him doing exactly that to Lithone, which is the first thing any audience saw of the movie and remains the most effective introduction any Transformers villain has had.

His interior is the more interesting part. It is a cathedral of machinery: chambers, conduits and reconditioning bays through which he can manipulate matter directly. The dying Megatron, cast adrift after Autobot City, is drawn inside along with Skywarp, Thundercracker, the Insecticons and Bombshell. Unicron offers a deal, and when Megatron hesitates, remakes him anyway. Megatron is dismantled and rebuilt as Galvatron, and his companions are recycled into Cyclonus, Scourge and the Sweeps. It is a genuinely disturbing sequence and it is the reason so much of the 1985 cast simply vanishes from the franchise.

His end is also interior. Having swallowed Hot Rod, Kup, Blurr, Springer, Arcee, Daniel, Wreck-Gar and eventually Galvatron, Unicron finds the war being fought inside his own body. Hot Rod takes the Matrix from Galvatron in Unicron's head, opens it, and the light tears the giant apart from within, transforming him into Rodimus Prime in the process. Unicron's severed head survives in orbit around Cybertron, a new moon, and returns in Ghost in the Machine when Starscream's spirit reanimates it.

• Unicron was voiced by Orson Welles in his final screen role; he died in October 1985, before the film was completed, and his lines were electronically processed afterwards.
• His name is a portmanteau of unicorn and Omnicron, and his design by Floro Dery gives him a planetary ring that becomes shoulder armour in robot mode.
• The third-season episode Call of the Primitives introduces Primacron, an ancient scientist who claims to have created Unicron, an origin the Marvel comics flatly contradict.
• Unicron's severed head remains in Cybertron's orbit for the rest of the series, effectively replacing the two moons he ate.
• No Unicron toy existed until 2003, seventeen years after the film, because a planet-scale transformable figure was considered unmanufacturable in 1986.