At dawn of Time, Primus commanded an army of mechanical warriors known as Mutacons to battle Unicron’s demonic hordes. They lost many but gained power and sentience until only 13 remained. The 13 Primes. Revered figures to Transformers but feared killers to the known universe.
Autobot pretenders from Masterforce!Metalhawk, Diver, Lander, and Phoenix. The heads of the robots become the un-armored human forms that then fit into the pretender shells armor!