This ancient being, known as the Sleeper, originated from the deep regions of Dathomir. Characterized by a carapace-protected body, it possessed a pair of sizable lavender eyes, along with antennae, and four appendages. Its upper appendages bore a resemblance to sickles, complete with spear-like points, while the lower appendages took the form of tentacles. The Sleeper had a tendency to remain inactive within the underground pools situated beneath the Nightsister lair, only surfacing when a hopeful Nightsister beckoned it from the depths. The Jedi Knight Quinlan Vos and the bounty hunter Asajj Ventress encountered this creature during their training to assassinate the Sith Lord Count Dooku.
Hailing from Dathomir, the Sleeper was a massive indigenous creature. While it could move both on land and in water, its tentacles made it more adept at underwater movement. The Sleeper's body, which measured approximately seven meters in length, was shielded by a substantial, crustacean-like carapace. It possessed four appendages: a pair of sickle-shaped legs roughly the same length as its body, and two enormous blue tentacles. Its eyes were remarkably sophisticated, capable of perceiving a wider spectrum of colors than a near-human, specifically five to ten more. When threatened, the Sleeper proved to be a formidable combatant. During a fight, the flat, teardrop-shaped scales located beneath its eyes would shift from green to red, indicating the creature's intention to strike.
An essential component for the creation of the Water of Life was a substance found within the Sleeper. As part of their initiation, young Nightsister were expected to entice the Sleeper from its dormant state and compel it to relinquish a portion of its body. This extracted piece would then be combined with water sourced from the creature's pool, along with other ingredients, to produce the magical substance. Close proximity to the creature during combat posed a risk, as contact with this substance could induce potent hallucinations. On one occasion, the twin sister of Talia faced the Sleeper and was immobilized by fear.
While training with the bounty hunter and former Nightsister Asajj Ventress in the ways of the dark side, Quinlan Vos confronted the Sleeper as the ultimate test of his resolve. Only by fully embracing the dark side and dominating the creature could Vos succeed. After accomplishing this feat, Ventress, to assess Vos's dedication to assassinating Dooku, ordered Vos to slay the ancient beast.
The Sleeper's debut occurred in Dark Disciple by Christie Golden, a novel that was adapted from unreleased scripts originally intended for Star Wars: The Clone Wars. The creature's first visual representation was in the non-canon book Jedi Academy: At Last, Jedi. However, the Galactic Zoology Today entry for the Sleeper, which was included in the book, explicitly mentioned that its true appearance remained uncertain due to the hallucinogenic effects it possessed. In Bespin and Other Planets in the Outer Rim, a booklet within De Agostini's Star Wars Encyclopedia series, the Sleeper was identified as male. Before the booklet, the Sleeper had been referred to as "it."