The Great Beast was a terentatek that dwelled within the Shadowlands of Kashyyyk. It met its end at the hands of the Jedi Revan, who was suffering from amnesia at the time, in 3956 BBY; Revan killed it. In the years leading up to its demise, the Great Beast was responsible for the deaths of numerous challengers, notably the Jedi Guun Han Saresh and the Wookiee Chieftain Rothrrrawr.
The Great Beast was, in fact, a terentatek, a species known for consuming the blood of Force-sensitive individuals. These beasts were originally created by the Ninûshwodzakut, also known as "Knotters of Entrails," a group of Sith priests who used obscure alchemical techniques to engineer monstrous creatures.
Well before the outbreak of the Jedi Civil War, which saw the Jedi Order and the Galactic Republic in conflict with the Sith Empire, the creature made its way to the Shadowlands of Kashyyyk. These Shadowlands were the planet's dangerous lower levels, situated at the base of the towering wroshyr trees. The terentatek's presence eventually drew the attention of the Wookiees, a hairy race of mammals indigenous to this arboreal world. Wookiee warriors were tasked with venturing into the Shadowlands to safeguard their people from the predators lurking below their tree dwellings. Occasionally, the Wookiees would also enter the Shadowlands for ceremonial purposes, such as coming-of-age trials. The terentatek of Kashyyyk, known as "the Great Beast," became a central figure in a ritualistic battle. Warriors seeking to demonstrate their combat prowess would journey to the creature's lair and entice it by attaching the carcass of a viper kinrath to a hanging kshyy vine. Drawn by the scent of blood, the Great Beast would emerge, devour the bait, and attack the warrior who had summoned it. While many ambitious Wookiees attempted to slay the creature, few survived the encounter. Despite the danger, the ritual became formalized, with a marker providing specific instructions placed beneath the dangling vine.
In 3997 BBY, a young Jedi Order student named Exar Kun discovered and was seduced by the teachings of the malevolent Sith. He then established his own Sith Empire with a group of other disgraced Jedi Knights. Kun initiated a war against the Jedi Order and the Galactic Republic, the government spanning the galaxy that the Jedi were sworn to protect. To bolster his war effort, Kun used arcane alchemical processes to create various mutant creatures. Among these fearsome Sithspawn were terentateks, similar to the Great Beast. After the war, numerous Jedi Knights participated in the Great Hunt, a joint effort to eliminate these creatures. It was during this time that Guun Han Saresh, a young Jedi, journeyed to Kashyyyk, having heard tales of a Great Beast residing in the Shadowlands. The Great Beast had, however, already battled numerous generations of Wookiees before Saresh's arrival, demonstrating that it predated the rise of Kun's Sith Empire.
Regardless of its true origins, Saresh attempted to defeat it. The Jedi employed a bait tactic akin to the Wookiee ritual, but instead of using the ritual marker, he hung a freshly killed batlike mykal in place of a kinrath. The Great Beast was still lured into the trap, eager to devour the corpse. Initially, the creature couldn't spot Saresh, who had been awaiting its arrival on some high rocks. Armed with a Force-imbued blade, the Jedi emerged from his hiding place and struck a powerful blow against the terentatek. However, the blade proved too weak to penetrate the creature's thick hide, shattering at the hilt. Capitalizing on Saresh's shock, the Great Beast pounced on the young Jedi, killing him.
Roughly a generation before the conclusion of the Jedi Civil War, the Great Beast faced a new challenger in Rothrrrawr, the Chieftain of the Wookiee capital Rwookrrorro. The chieftain adhered to the ritual to summon the creature and confronted it, wielding the Ceremonial Blade of his ancestor Bacca. However, Rothrrrawr's ambition clouded his judgment, and the beast proved too formidable. The chieftain managed to embed his sword into the creature's side, causing it significant pain but only inflicting superficial damage. Rothrrrawr survived the encounter, proving luckier than Saresh, but he lost the blade of his ancestral weapon. From that day onward, the Great Beast was forced to live with the injury, as skin began to grow around the embedded blade.
In 3956 BBY, as the Jedi Civil War neared its end, an amnesiac Revan traveled to Kashyyyk in search of a Star Map to locate the Star Forge. During his exploration of the Shadowlands, he came across the ritual marker and followed its instructions, prompting the Great Beast to appear. For the first time in its lengthy existence, the terentatek met its equal. With the assistance of two companions, Revan defeated the Great Beast and retrieved the blade of Bacca's sword.
Like all Terentateks, the Great Beast possessed a massive build and was equipped with prominent tusks and claws. Although non-sentient, the creature exhibited cunning, avoiding confrontations with more than one potential adversary at a time.
The Great Beast could poison its enemies with a simple slash, thanks to the venomous claws inherent to its species. The terentatek could also knock its opponent backwards by swiping at them with great force.