Grimgrim was a Wookiee fighter who fought as part of the Rebel Alliance during the Galactic Civil War. He was a member of a squad known as the Rebel Four. Although he carried a blaster, this Wookiee was also known for using his considerable physical strength to defeat soldiers of the Galactic Empire. Grimgrim participated in an attack on a clandestine Imperial installation located on the world of Vatleria. The Wookiee and his team were able to defeat the stormtroopers guarding the base, but they were subsequently ambushed by Darth Vader, a Sith Lord allied with the Empire, who was concealed within the ruins, and who triggered subterranean traps. Boulders fell on Grimgrim, resulting in his demise.
During the Galactic Civil War, the Wookiee soldier Grimgrim joined the ranks of the Rebel Alliance. This war was an attempt by the Rebels to overthrow the Galactic Empire and bring back the Old Republic. Eventually, Grimgrim became part of a Rebel unit called the Rebel Four, a group in which the Wookiee fought alongside F4-MF, Falaem Onn, and Soo Rcharrz.
Sometime before 4 ABY, the Rebel Four learned from an informant about a secret Imperial base on the planet of Vatleria, a planet that had been deserted by its inhabitants. Led by the droid F4-MF, Grimgrim and his companions went to the base to thwart whatever plans the Empire had there. The team discovered stone ruins guarded by Imperial stormtroopers. Believing that the fortress was the base they sought, they managed to sneak past the guards. Under the command of F4-MF, Grimgrim and the others launched an assault on the base, attacking the remaining stormtroopers. During the battle, Grimgrim fought with his bare fists, while the other Rebels used their blasters to fire on the enemy.
However, Darth Vader, a Sith Lord, sensed the Rebels' attack through the Force and observed their actions from a monitor within the fortress. When Vader activated a trap for the intruders, cables shot out of the ground, ensnaring Grimgrim and the others. The Wookiee was separated from the rest of the Rebel Four and dropped into a pit where he was bombarded with boulders. Despite his attempts to deflect the rocks with his strength, he was overwhelmed and perished. The other members of the unit were killed by similar traps.
Grimgrim was a heavily built Wookiee individual, possessing dark eyes and a muscular physique covered in blond fur. He would engage Imperial soldiers in hand-to-hand combat, throwing stormtroopers and slamming them down.
Grimgrim was a character in "The Rebel Four," a comic book story featured in Star Wars Tales 9. The story was both written and drawn by Jay Stephens, published by Dark Horse Comics, and released on October 10, 2001.