Before the Great Exodus, Grimlock was captured by , a Decepticon charged with seeking out new forms of power and destruction in the universe. His eye was drawn to Earth, where he spotted dinosaurs, inspiring him to change Grimlock's alternate form into that of a cybertronian t-rex, with the intention of creating a powerful new warrior. However, Grimlock's greater power would compensated by a smaller intelligence. Although his processor was badly damaged by the process, Grimlock, using his new-found power, escaped the laboratory, and is now on the loose.
Grimlock, bound within , awoke to find offering to join forces against . Grimlock, who was distraught with the changes done to him, violently refused. While discovering that his transformation into his new beast form was enabled only by his levels of rage, he and began searching for the rest of their group. Ultimately, all were found except . Battling through , Grimlock reluctantly contacted from one of Shockwave's observatory decks, and warned him that Shockwave was attempting to open a portal soon. Shockwave himself was engaged by Grimlock just as the portal took both of them through it, leaving the three remaining "" behind.
Grimlock is a member of the who appears in . He is adressed as a "King" by his fellow dinobots, he believes justice is to be attack first and ask questions later in other words "Might for Right". Not concerning with trophies but only glorius victories. His robot mode is a Knight-Esque apperence and armed with a powerful mace-staff.
While on 's ship, Grimlock was briefly seen when Lockdown was imprisoning and talking to . It was later revealed by Lockdown that this place is the prison for the Legendary Knights, which were the . Later, when the Autobots, Cade Yeager, and Shane Dyson arrived to rescue Optimus and Tessa, flew this prison away(since it was a detachable part of the ship) and sent the Autobots to a trainyard while and were fighting against Lockdown's mercenaries. Later, when the ship arrived at Hong Kong and was ready to pick up KSI's CEO, Joshua Joyce, and the Seed, a Trax arrived and shot the ship, sending it pummeling towards the nearby Wulong Valley. Soon, Optimus freed the Dinobots and asked for their assistance to the Autobots. Grimlock, however, refuses and began attacking Optimus. Within minutes, Optimus beat the giant warrior, and Grimlock decided to join forces. Then, the Dinobots and the Autobots led a widespread rampage in which destroyed most of 's forces. After the rampage, Lockdown returned and attempted to retrieve Optimus, Grimlock, and the others with a giant magnet. However, Optimus saved the day by shooting towards the magnet. Later, his efforts were focused on blocking a bridge so that Galvatron cannot get the Seed. After the battle, Grimlock and his Dinobots left the Autobots with good terms, running off to the countryside during sunset.
|Antagonists of Season 3|
|Emilio Smith · William Hamilton · Guardians · The Boss and his minions · Trolls · Grimlocks · Belthazor · Ruth Cobb · Abbey · Troxa · Vinceres · Andras · The Triad · Krell · Kierkan · Terra · Ari, Freckles and Jersey · The Nothing · Eames · Kellman and his Wrestlers· Tom Peters · Dantalian · Zile · Prue, Piper and Phoebe Halliwell · Sutter · Jack · The Seekers · Shadow · Lukas · Brotherhood of the Thorn · Banshee · Shax · Alice Hicks · The Source of All Evil|