Nebulos
Nebulos (sometimes called Nebulon) is a planet inhabited by organic lifeforms, most notably a race of humanoids called Nebulans or Nebulons. These beings have found themselves involved with the Transformers in several different dimensions within the multiverse.
Generation 1
Marvel Comics Continuity
A planet of humanoids that had lived without war for thousands of years. A group of Autobots led by Fortress Maximus sought to relocate to Nebulos in order to escape their own millenia-old conflict on Cybertron, but their arrival created dissension and mistrust within the Nebulan community. The arrival of a group of Decepticons led by Scorponok soon afterward only escalated these tensions, and Nebulos' age of peace was lost as citizens binary-bonded to Transformers on both sides of the conflict to become Headmasters and Targetmasters.
Realizing the damage that was being done to Nebulos' once-peaceful culture, the Autobots abandoned the planet to join Transformers already on the planet Earth, believing (correctly) that the Decepticons would pursue them off-Nebulos.
After this the citizens of Nebulos tainted their own energy sources so as to be poisonous to any Transformers that might seek to return to their world. When Decepticons Darkwing and Dreadwind arrived soon after the departure of the other Transformers, they soon found themselves victim of this poisoning, and lay dormant for a time. They were later revived by Nebulan traitors Hi-Test and Throttle, who had stolen power-conversion plans that eventually created the Powermasters. Hi-Q, the creator of this process, eventually binary-bonded with a reborn Optimus Prime, and several of his staff joined with other Autobots, in order to combat the threat posed by Darkwing and Dreadwind. They, too, eventually left Nebulos to join the other Transformers on Earth.
Nebulans are shown to have either purple or orange skin in the comics.
U.S. Animated Continuity
Nebulos was a world who's inhabitants were enslaved by the Hive, a group of eleven Nebulon telekinetics whose focus on development of their mental powers had cause their bodies to wither, led by Lord Zarak. The populace was mainly forced to do routine farm work, watched over by the machines which the Hive controlled telepathiclaly.
Several Transformers crash on Nebulos. A small band of Nebulon rebels, led by Gort, capture the Autobots, believing them to be Hive machines. The Decepticons are captured by the Hive. Convincing the rebels that they are not Hive machines, the Autobots volunteer to help, offering up four of their own to serve as Headmasters, with Nebulon partners inside their heads to serve as secondary operators.
Zarak demands his own Headmasters, but Cyclonus only wishes to offer up the Decepticon animals for this. The rest offer their weapons, which Zarak willingly accepts. The Autobots learn of this and adapt the new Targetmaster designs.
In the climax, Zarak rebuilds a Hive facility into the large Transformers Headmaster body Scorponok, only to be countered by Fortress Maximus, an old Hive city converted into a Headmaster body by Spike Witwicky and Cerebros. Defeated, the Hive and the Decepticons fled in Scorponok.
Nebulans in the cartoon are depicted with green skin and either dark green or white hair.
Dreamwave Comics Continuity
Unicron Trilogy
Following the conclusion of the Energon War, the Autobot Jetfire spent some time on the planet Nebulon. There he picked up a new accent from the locals, which to human ears resembles that of Australians.
Little else is known of this version of Nebulon, other than that its pea soup is notably thick.