Inhumanoids
The Inhumanoids are a race of inhuman monsters that live in the center of the Earth. Led by the monstrous Metlar, they wish to invade the surface world!
They appear to co-exist with the Transformers in at least one universe.
Fiction
Shattered Glass
At some point in the recent past, the Inhumanoids attacked. The American government promised this would never happen again. Eye in the Sky
Trivia

- The Inhumanoids was another Marvel/Sunbow co-production. The omnipresent Hector Ramirez appeared in both Transformers and The Inhumanoids; if you follow the theory of a unified Hasbro cartooniverse (see below), the Inhumanoids co-exist with the Transformers.
- The Inhumanoids also had their own short-lived comic. Reprints of it ran as a back-up strip in Marvel UK's The Transformers, #103-118.