Hyenaxes were savage, meat-eating, dog-like creatures originating from the world of Vaal. Their hides displayed various brown hues, marked by dark stripes along their backs, and a mane of hair adorned their necks and upper backs.
Hyenaxes adhered to a pecking order for leadership and were pack animals. Should the alpha be slain by another being, that being would instantaneously become the pack's new leader. This characteristic extended beyond their own kind, as demonstrated when a hyenax pack trailed Darth Vader, a Human, subsequent to his lethal confrontation with their alpha.
Following the Battle of Yavin in 0 ABY, the Sith Lord Darth Vader experienced a crash landing on Vaal. A hyenax pack ambushed him there. Vader eliminated several hyenaxes, including their leader, causing the rest to retreat. Later that night, Vader was encircled by the canines, who presented him with the corpse of their previous alpha, a role Vader had inadvertently inherited through his act of killing it.
The following day, the pack launched an assault on a large creature, resulting in multiple hyenax deaths. Enraged, Vader dispatched the creature using only his hands.
The pack then shadowed their new leader to the Imperial Relay Outpost V-798, where they slaughtered the entire crew after Vader left the planet aboard the station's sole shuttle.