One of the most memorable groups of Generation 1 in 1985 were the Dinobots. Introduced in the second series, as Transformers was coming to its height, the Dinobot Grimlock transforms into a robotic Tyrannosaurus rex.

US Patent for G1 Grimlock


Grimlock, like all the Dinobots, started his existence in Takara’s Diaclone in 1983. As part of the sub-series Dinosaur Robo, he was No. 1 Tyrannosaurus. This version was only slightly different than the G1 release. Its die-cast waistplate was painted blue, and the sword was made of chromed hard plastic. This version included a small plastic and die-cast driver that could be inserted in the rotating translucent seat on the diosaur’s back. Not surprisingly, Koujin Ohno, inventory of so many G1 favorites is listed as the inventor on Grimlock’s US Patent.


Grimlock transforms into a robotic Tyrannosaurus, with a mostly silver body. His tail and arms are decorated in silver chrome, and he uses gold chrome for his toes, belly, and the mechanical pieces inside his translucent gray neck. As with all toys of this period, Grimlock depicts the Tyrannosaurus standing erect, dragging his tail along the ground. He features articulation at the neck, jaw, hips, and knees, making him one of the most articulated Dinobots, if not one of the most articulated G1 beast alternate mode toys. His transformation is simple but somewhat nuanced. His upper torso forms “wings” behind his shoulders, while his belly and legs become the muscular-looking chest and arms. The rear half of the dinosaurian mode becomes Grimlock’s large, wide-stance legs. Grimlock can wield a combination of his soft rubber sword, his double-barreled blaster, or his handheld missile launcher.

Collector Notes

For a former Diaclone toy, Grimlock is relatively sturdy, but he does have some minor faults. The most notable of these are the small clips on top of the dinosaurian chest. These clips hold the dinosaur head in place, and due to the mobility of the two chest plates, misalignment could cause one or both clips to break off. Also, the translucent center of his chestplate can occasionally be pulled off.


Grimlock’s mold was changed slightly during the course of his production run to correct some ongoing problems. The dino head received a stop tab that prevented over-rotation at the neck joint, and the dino chest halves got a tab and hole to clip them together and prevent slippage.


Grimlock was available in 1985. Due to the popularity of the Dinobots, he was available again in 1986. He was available in 1991 in Europe as part of the Classic Dinobots. He was also available as a mail-away exclusive in Japan during Operation Combination in 1992.

Redecos & Retools

Grimlock’s mold was originally used to create Diaclone Dinosaur Robo No. 1 Tyrannosaurus in 1983. The mold was used again to create G2 Grimlock in 1993, in three variations: blue, turquoise, and silver. The G2 versions did not include the missile launcher and missiles. The silver version is very similar to the G1, but is discernable by some minor molding differences and the word “Autobot” with a log tampographed on the inside edge of his robot leg.>