Grimlock is egomaniacal, impatient and dimwitted, but he is a powerful soldier. Grimlock was a gladiator from Kaon, but chose to join the Autobots early on in the war. His has some issues to work out with Optimus Prime and shock and awe approach to combat meant he was not regarded as a great leader, but he has survived long enough to earn a high rank and command of the Lightning Strike Coalition. After being captured by Shockwave, they were reformatted into the Dinobots. He is good friends with Swoop, Slug, Sludge, & Snarl and wields his prized energon sword in battle.
- Voice actor: Gregg Berger (English)
Grimlock is known for not following orders or trusting in Optimus Prime's ability to be an effective leader. As the leader of the Lightning Strike Coalition Force, Grimlock enjoys smashing things first and asking questions later. Due to Shockwave's experiments, Grimlock has been left with a malfunctioning voice processor and an alt-mode inspired by a distant primitive world.
War for CybertronEdit
Grimlock and Swoop were two powerful best friends who'd apparently taken no side in the war for the planet. Optimus Prime, leader of the Autobots, came to them to recruit them to the cause. Grimlock dismissed the Decepticon threat, claiming they were "too stupid" to mess with him and Swoop. The Autobots tried to explain that the Dark Energon could ravage Cybertron permanently, but Grimlock and Ironhide almost came to blows. Optimus began playing to Grimlock's self-centered ego, saying no one was stronger than Grimlock and Swoop, to the former's pleasure. Ironhide and Bumblebee joined in, but adding that with Dark Energon, Megatron and his forces could be stronger than Grimlock and Swoop.
Grimlock decided that he and Swoop would consider joining the Autobots, but just as negotiations were to begin, Grimlock noticed Swoop had been missing since the Autobots arrived. Grimlock said they would speak once Swoop was rescued from the Decepticons. Once Swoop was safe, he immediately joined the Autobots in gratitude. Grimlock declared he wouldn't join the Autobots yet, but tag along to protect his best friend.
Grimlock subsequently actively participated in the campaigns to save the Core of Cybertron. Grimlock said that even though the Decepticon army was waiting for them at the Core, all they'd wait for from him was a butt-kicking. Ironhide pondered aloud if it was a good idea to bring Grimlock along, but as Optimus put it, "Do you want to be the one to argue with them?"
Grimlock was apparently wandering around an Energon purification station the Autobots had been using, and picked a fight with the Autobots. To his utter surprise, the Autobots beat Grimlock, and he finally joined them.
Fall of CybertronEdit
Before the Great Exodus, Grimlock was captured by Shockwave, 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 Shockwave's lab, awoke to find Starscream offering to join forces against Megatron. 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 Swoop began searching for the rest of their group. Ultimately, all were found except Sludge. Battling through Insecticons, Grimlock reluctantly contacted Optimus Prime from one of Shockwave's observatory decks, and warned him that Shockwave was attempting to open a space bridge portal soon. Shockwave himself was engaged by Grimlock just as the portal took both of them through it, leaving the three remaining "Dinobots" behind.