Nebulos

Nebulos is the only alien world in G1 given a real gazetteer, and it exists to explain a toy gimmick: why would a Transformer's head be a small person. The answer, in Marvel's Headmasters series, is binary bonding. Fortress Maximus and a group of Autobots who have simply had enough of a four-million-year war leave Cybertron for Nebulos, a world that has been at peace for thousands of years. Their arrival poisons it. Nebulan society fractures over what to do about giant armed refugees, and when Scorponok's Decepticons follow, the planet's peace ends. Nebulans on both sides bond with Transformers, becoming their heads and their weapons.

The Autobots eventually recognise what they have done and leave for Earth, correctly reasoning that the Decepticons will follow them off Nebulos. The Nebulans then poison their own energy sources so that no Transformer can ever refuel there again, which catches Darkwing and Dreadwind when they arrive later. Hi-Q, the Nebulan who developed the power-conversion process behind the Powermasters, ends up binary bonded to a rebuilt Optimus Prime.

The cartoon's Nebulos is a different planet with the same name. Its Nebulons are green-skinned humanoids enslaved by the Hive, eleven telekinetics whose bodies have withered, led by Lord Zarak. In The Rebirth crashed Transformers take sides in a slave revolt: the Autobots offer four of their own as Headmasters bonded to Gort's rebels, Zarak converts a Hive facility into Scorponok, and Spike Witwicky and Cerebros convert an old Hive city into Fortress Maximus.

• Nebulos is the only non-Cybertronian G1 world with a full published gazetteer: Koraja, Splendora, the Nursery, the Arvassian Range, the Folassian Forest, the Plains of Thok and the Mercury Gardens of Melanossus.
• The comics and the cartoon share the planet's name and almost nothing else. Marvel's Nebulans are willing partners; the cartoon's are slaves of the telekinetic Hive.
• The cartoon's robotic Hive elders are drawn identically to the Lithonians from the 1986 film, a straight model reuse.
• Nebulans wearing robotic armour is how the toys were originally presented, which left every continuity free to invent what the beings underneath looked like.
• Marvel's Nebulos storyline is the franchise's clearest anti-war statement: the Autobots leave because their presence is the problem.