Trans-Organics
The Trans-Organics were cybernetic creatures created by the Quintessons, a precursor to the Transformers as a servitor race. The Trans-Organics turned out to be unstable and hard to control, and the Quintessons abandoned them, destroying all they could and containing those they couldn't, sealing them within a chamber in the depths of Cybertron (Seibertron). The most powerful Trans-Organic, known later as the Dweller, destroyed one of the three faces of their Quintesson creator, before it too was imprisoned.
They were later released in the year 2006 (2010) by Galvatron and other Decepticons (Destrons), who were tricked by the Quintesson who created the creatures. The Dweller slew the other Trans-Organics, but it could only be sent into space, where it found its creator's spacecraft and attacked. The Dweller was not seen again, and no other Trans-Organics are known to exist.
References
- Transformers: "The Dweller in the Depths" (1986)