Grimlock is a supporting character in Transformers: Age of Extinction and a minor character in Transformers: The Last Knight. He is the leader of the Dinobots who transforms into a mechanical Tyrannosaurus Rex and is part of the Legendary Knights.
Grimlock found himself being the guinea pig for Optimus' Dinobot-riding lessons. To his irritation, Optimus rudely beckoned him to move forward, and was thus thrown into a barn. Optimus' mood did not improve much, but Grimlock's did, as it was now time for him to ride Optimus. The Autobot leader proved a much more compliant steed, to Grimlock's joy.
Age of Extinction
Grimlock was a prisoner aboard Lockdown's ship until the Autobots detached that section and flew it to China, though Optimus did not inform his troops of their presence. When Galvatron's new Decepticons shot down their ship, Optimus went to recruit the Dinobots for their aid. Optimus was nevertheless amazed that the "legend" existed, and freed Grimlock and his men. Optimus explained to Grimlock that the Creators intended to wipe them all out, and urged them to stand with him, or refuse and die. Grimlock immediately challenged Optimus, but despite his immense size and strength, was bested in combat. Grimlock submitted to Optimus' lead, and allowed the Autobot leader to mount him. Grimlock and Optimus led the Dinobot-Autobot charge into Hong Kong, where Grimlock killed many Decepticons with ease. Grimlock later helped escort the Seed to a safe location, but Lockdown arrived and turned his tractor beam on them. Grimlock and the Dinobots would've been captured once again had Optimus not destroyed the tractor beam with a well-placed shot. Optimus ordered Grimlock and the others to flee while he fought Lockdown. The group subsequently held the line on a nearby bridge until Optimus, Bumblebee, and their human allies triumphed and killed Lockdown. Optimus granted Grimlock and the Dinobots their freedom, and Grimlock happily departed with his team for parts unknown.
The Last Knight
In the years following the battle in China, Grimlock along with Slug and 3 new mini-Dinobots joined the Autobots in hiding at Cade Yeager's scrapyard. Unfortunately, he developed a habit of stealing the local sheriff's cruiser and using it as a chew toy. On the day Cade encountered the dying knight Steelbane, he returned to find an angry sheriff demanding the return of his vehicle. Grimlock tried to hide the cruiser by eating it but was eventually berated into vomiting it back up. Cade then turned on his assistant Jimmy for not keeping Grimlock under control, who pointed out that without Cade the Autobots were uncontrollable and Grimlock had tried to eat him at least once. Grimlock later relaxed in the scrapyard while Cade called his daughter Tessa.
The next day, their refuge was discovered by the Decepticons and TRF forces. As their enemies prepared to invade, Cade and the Autobots escaped to a nearby town to carry out their emergency plan. Grimlock joined Slug in laying a trap for the pursuing TRF forces, bursting from beneath the road leading to the town and destroying the convoy. Grimlock then made his way to the town in time to save Cade and Izzie from Barricade, swatting the Decepticon with his tail, before slamming him into the ground. As Dreadbot ran in to assist, Grimlock snapped him up and killed the Decepticon bank robber. Grimlock remained in America after Cade was taken to England by Cogman and did not participate in the final battle on Cybertron. It is possible he returned to Cybertron after the battle.
Unlike any of his other incarnations, movie-verse Grimlock doesn't speak. Also unlike other incarnations he has Horns on his head
Grimlock, in T-Rex mode is approximately 3 times the size of a real tyrannosaurus.