The Mutacons are Shifter Transformers who have been blessed (or cursed) by their discovery of the original Transformation Cog of Amalgamous Prime, one of the first Thirteen Transformers. Exposure to it has granted them super-transformational abilities of infinite-transformation and infinite-combination.
Mutacons tend to be silver and blue in color. Individual Mutacons range in size from small Mini-Cons to approximately the size of Bulkhead. Personality-wise, they tend to be friendly, inquisitive, light-hearted, and easily amused. Though they have been referred to as pirates, and do have friendly relations with the Star Seekers, in their encounter with the Autobots they acted more like friendly traders, happily offering to trade energon for new information and forms.
Any Mutacon can change into anything they know, can see or sample, and merge with any number of other Mutacons to form bigger, more complex modes. They can also merge with non-Mutacon Transformers, a process which allows each to understand what it is like to be the other. From such a merger the Mutacon gains the ability to copy the other's form completely and can grant the normal Transformer a portion of the Mutacon's transformation and healing powers.
There is, however, a dark side to the Mutacons' gifts. They are slowly and involuntarily merging in to one composite being, losing their individual identities and memories. There is a fear that if the process is not reversed, they will eventually become a single amorphous blob-being. That might not be terrible, but it's something they would rather avoid.
They travel the stars as a fleet of massive starships composed of their combined bodies, searching for Amalgamous Prime in hopes he can cure their condition.
The Transformers who would become the Mutacons fled the destruction of the Neutronia colony in starships when the Rust Plague that ended the Golden Age hit. In space they found the Transformation Cog of Amalgamous Prime near a black hole. Fearing the destruction of the ancient treasure, they took it with them. The mystical object granted them infinite transformation and combination abilities, and accordingly they renamed themselves to match their new powers. However, they soon discovered they were beginning to involuntarily merge into one being, slowly losing their own personalities and memories.
Eventually they traveled the stars as a fleet made from their own forms and had garnered a reputation as pirates.
Optimus Prime and the Ark crew met their fleet in space where the friendly enthusiastic and outgoing Mutacon named Mercury communicated with them and offered to trade energon stores in return for help in locating Amalgamous Prime or for the chance to merge with Optimus Prime to learn how to change into his form. (Bulkhead thought that sounded "kinky"). She caused a moderate uproar of whistles and cat-calls among the male Autobots when she visited Prime in person. The Matrix downloaded a history of Cybertron since the Rust Plague to her and she fell on the floor laughing at how dumb the Decepticons were.
Prime promised to help the Mutacons solve their shape-changing problem after the Decepticons were no longer a threat. That was good enough for Mercury, and she happily returned to the others. Their combined ship form laughed in space and mischievously set about delaying the Autobots pursuers so the Ark could escape on their way.
- Thundertron does not believe in mystical artifacts or the Primes and so he refuses to believe the Mutacons' story of their origins. He thinks they were all mutated by exposure to a neutron star. In return they think he's dumb as a post.
- When told about the Quintessons the Mutacons say they know about those "law-obsessed" stick-in-the-muds and aren't impressed. They tried being like that long ago but it was "boooooooooooooooooooring." Which to the mercurial and faeish Mutacons may be worse than death.