The Shadow creature was an energy-based sentient creature.
During the time of the Old Republic, the shadow creature traveled to the planet Oblis, in the Cularin system, drawn to the power of the Darkstaff, a Sith artifact that was located on the world. The creature settled above Oblis and began to meld itself with the atmosphere, where it started to grow larger. The native Oblee felt threatened by the creature and in an attempt to rid their world of it, they created three focusing crystals to harness the power of the Darkstaff. However, when they fired the weapon at the shadow creature, the creature and the Oblee were thrown out across the galaxy and Oblis was destroyed.
Thousands of years later, the creature returned to the Cularin system after sensing the power of the Almas Sith fortress, a Sith Temple that was constructed by the Sith Lord Darth Rivan. However, by the time the creature arrived in the system, Rivan had been defeated and the presence of the dark side had waned. The creature took refuge in the Cularin system asteroid belt, which had formed from the remains of Oblis, and entered a slumber. However, it was stirred from its sleep by the construction of the Almas Academy on Almas and by the Confederation Rock Rush, an event that was caused by the opening up of the asteroid belt in circa 31 BBY. The creature began drawing power from passing starships and was eventually able to free itself from the asteroid that it lay within.