Mutant T-Rexes originated as T-Rexes living in the jungles of Dinosaur Island and Adventurers' Island. These T-Rexes were hunted and captured by XERRD operatives and mercenaries, then brought to the Dino Island Laboratory by Dino Track Transport. There, they were mutated by experiments involving the Maelstrom into Mutant T-Rexes.
When the Dino Attack began, Mutant T-Rexes spread across the LEGO Planet by means of continental migration, Michelle Glados's teleport pads, or even sneaking aboard large cargo ships. Although Mutant T-Rexes are the rarest of Mutant Dinosaurs, they are the most feared and destructive, even prompting the Dino Attack Team to specifically modify the T-1 Typhoon helicopters to stand a chance against these creatures.
Mutant T-Rexes typically arrive at the climax of major Dino Attack battles. Six Mutant T-Rexes attacked a Power Station, forcing Rex and Reptile to defend the building with Iron Predators until the founding members could arrive in a T-1 Typhoon. A pair of Mutant T-Rexes also destroyed the gate of the Aztec Village shortly before a triceratops stampede ended the battle. During the battle for the Temple of Hotep III, a pair of Mutant T-Rexes were responsible for destroying the Renaissance.
Although some Dino Attack agents have taken up the hobby of taming Mutant Dinos, the Mutant T-Rex has proven exceptionally difficult to tame. Only three successfully-tamed Mutant T-Rexes have been documented, and each specimen had to be raised from a young age. One T-Rex named Maw was tamed by Rex, but this act led him to be temporarily discharged from Dino Attack Team after Maw accidentally went on rampage and nearly killed the founding members; shortly afterward, Maw was killed in fight against a full-grown adult Mutant T-Rex. The other two tamed T-Rexes are the siblings Tex and Crunchbite, raised by Fullmetal as unique specimens that were further mutated by Green Goo exposure; Tex was also transformed by Valencia's dragon magic, making her a unique dinosaur/dragon hybrid.
Despite this, not all Mutant T-Rexes are hostile towards minifigs. At LEGO Studios, a T-Rex actor named Rex (not to be confused with the Dino Attack agent of the same name) was captured and mutated by XERRD, but he saved a squad of Dino Attack agents from a wild Mutant T-Rex. Tex and Crunchbite's father, Ragnarok, assisted GAIA Squad during the battle for Mt. Bricklake. Cyrista's Bane notably switched sides during the final battle after Dr. Cyborg freed it from XERRD's programming.
The most notable Mutant T-Rex is the creator of the Mutant Dinos himself, Dr. Rex, after a freak accident involving a Creative Spark-switching machine. Calling himself "Alpha Rex", Dr. Rex clad himself in silge armor and personally led the Mutant Dino army on attacks in the Goo Caverns and LEGO City. After being possessed by the Darkitect, Dr. Rex was nearly invincible and could only be killed by the Einstein Device.
After Dr. Rex's defeat, any surviving Mutant T-Rexes scattered across the LEGO Planet. Dino Attack Team spent their post-war efforts hunting down and capturing Mutant T-Rexes, along with any other remaining Mutant Dinos.
Mutant T-Rexes are the supreme rulers of the Mutant Dinosaurs. They are massive and, due to being able to bite through steel and cause destruction with a sweep of its tail, easily capable of demolishing dozens of vehicles and buildings before being stopped. Vehicles less then the size of a Iron Predator would have practically no chance against these mammoth Mutant Dinos without backup. Its eyes are capable of firing lasers, thus allowing the T-Rex to fight off a T-1 Typhoon or other aerial attackers, and its mouth literally has a furnace built into it, allowing it to disintegrate anything its jaws close on.
Notable Mutant T-Rexes Edit
- Amanda Claw: A Dino Attack agent who was temporarily mutated by Mutant Dino Serum.
- Crunchbite: Tex's younger sibling who was mutated by exposure to Green Goo. His birthname was Kardas. He died after the final battle.
- Cyrista's Bane: A biomechanically-augmented Mutant T-Rex designed by Matthew Cyrista and used in battle by XERRD before defecting to Dino Attack Team.
- Dr. Rex: The leader of XERRD who mutated himself after accidentally switching bodies with Rex.
- Maw: The only Mutant T-Rex successfully tamed by Rex Alexander. Maw was killed in combat with a larger, stronger Mutant T-Rex.
- Ragnarok: Tex and Crunchbite's father who lived in the Goo Caverns. Along with Eno Saurson, Ragnarok assisted the GAIA Squad during their escape from a XERRD arena. He died before the end of the war.
- Rex: A LEGO Studios dinosaur actor who was mutated during the Dino Attack. His mutation was cured after he was rescued by Dino Attack Team and brought to the Carlsbad outpost.
- Rex Alexander: The "prototype" Mutant T-Rex, the first specimen to be mutated but without any Maelstrom-granted powers. After his mutation was cured and his body was switched with Dr. Rex, Rex is no longer a Mutant T-Rex.
- Snake of Spades: A Dino Attack agent who was mutated by Mutant Dino Serum.
- Tex: Fullmetal's tamed T-Rex who was mutated by exposure to Green Goo and magically turned half-dragon by Valencia.
- Zorikk: A Dino Attack agent who was temporarily mutated by experiments involving Green Goo.
- In the online LEGO Dino Attack game, yellow-bellied Mutant T-Rexes could spawn Mutant Raptors and red-bellied Mutant T-Rexes had a fire-breathing attack. Neither ability is considered canon in Dino Attack RPG (here, Mutant T-Rex scale color is merely aesthetic), although the latter may have been the inspiration for Dr. Rex's Maelstrom-fueled fire breath.