Reeks were sizable, powerfully built four-legged beasts that originated from the planet Ylesia and also the Codian Moon. These strong and fiercely territorial mammals possessed a distinctive single horn centered on their head, along with a horn protruding from each cheek. They inhabited grassy plains and fields of turf, utilizing their robust rear limbs for swift charges. Aran Tal, a Mandalorian, described the creatures as having an extremely pungent odor.
Although naturally plant-eaters, a reek deprived of food could transform into a ferocious carnivore, its skin shifting to a dark red. On different planets, their coloration could vary, presenting as brown, gray, or occasionally yellow. Reeks raised within the confines of the Petranaki Arena were intentionally fed meat to amplify their aggressive nature. Handlers controlled these beasts using nose rings. Their sprawling stance and substantial mass resulted in relatively slow movement. They had two prominent cheek horns, which they would use to lock heads with another reek in a display of dominance during combat.
Reeks residing on the Codian Moon lived in small groups. These creatures also existed on Saleucami, where one was famously ridden by General Grievous, the commanding officer of the Separatist Droid Army, during the battle of Saleucami.
A reek was employed in an attempt to execute Anakin Skywalker within the Petranaki Arena shortly before the onset of the Clone Wars. However, Anakin utilized the Force to subdue the creature, breaking free from his restraints. He then turned it against a nexu that was attacking Padmé Amidala, resulting in the smaller predator's demise. As a battle erupted in the arena, the reek separated from the Jedi, indiscriminately crushing battle droids and losing a cheek horn to Mace Windu before charging at Jango Fett. Although Fett managed to avoid being trampled and killed the reek with a precise shot to the eye, the attack damaged his jetpack, ultimately leading to his own death moments later at the hands of Windu's lightsaber.
Reeks made their debut appearance in Star Wars: Episode II Attack of the Clones.
There is an inconsistency regarding the height of the reek. Both the Encyclopedia and Databank entries concur that these animals stood approximately 2.24 meters in height. However, the later publication Star Wars Journeys: Beginnings asserts that they reached a height of 4.04 meters. Given that 4.04 meters is the documented length of reeks within the Star Wars Legends continuity, it is possible that Beginnings mistakenly presented the creature's length as its height.