Onyx Prime is the first of the Cybertronians with a Beast Mode and thus the ancestor of the Predacons and one of the Thirteen. He is not known to have wielded any weapons, but possessed the Triptych Mask as his personal artifact.
He was among the Thirteen created by Primus to battle and win against Unicron and see the activation of the Well of Allsparks. Unfortunately, during the War of the Primes he was fatally injured, and chose to enter the Well so that the proximity of Primus' spark would sustain his existence. Badly wounded as he was, he was carried into the Well by Optimus Prime, who sought to be reborn as a lesser Cybertronian, and with his friend Micronus Prime accompanying him. He would subsequently employ his Triptych Mask to give varied forms to the Cybertronians who emerged from the well, including the original Predaking and the other Predacons. It is unknown what became of him later, though curiously new Predacons ceased to emerge from the Well following the Great Cataclysm.
Onyx has something of an "Alpha" mentality, as he enjoyed the advantage that his strange abilities sometimes gave him over the other Primes. Despite this, he is unique in being the only member of the Thirteen who enjoyed a friendship with all the others, even the temperamental Megatronus.
According to some screenshots, Onyx is very similar in appearance to that of a winged centaur, which could be his Beast Mode, along with the added feature of a bat-like head.
- It is revealed in Transformers: The Covenant of Primus that name of the Beast Prime is Onyx.
- The IDW Comics featured a version of Onyx Prime who was more similar in personality and role to the Transformers: Prime portrayal of Predaking.
- Since he is the first known Cybertronian to possess a Beast Mode of any sort, its is possible that any Cybertronian-based mechanical beings, specifically those such as the Predacons, Insecticons, Dinobots, Sharkticons, Chompazoids, Amphiboids, Corvicons, Buffaloids, Skunkticons, Croctobots, Orangucons and Shrimpticons are all somehow descended from and related to Onyx himself.