Diabolicus

Diabolicus is an alien from the Unicron Trilogy continuity family.

You can't see me!

_{This character has no official visual representation in any Transformers product or media... yet, at least.}

Prince Diabolicus is somehow associated with the nefarious Assassin Synod.

Fiction

Spacewarp's Log

Spacewarp considered Prince Diabolicus to be one of her many arch-enemies. Spacewarp's Log (1), 2015/10/31