The Zalkor is the secondary antagonist yet major villainous force in the Count Abyss story arc of Marvel comics, focusing on the cosmic hero known as Adam Warlock and the infamous Infinity Gems, of which the Soul Gem became a central part of said story.
The Zalkor is an ancient demon of incredible might that can grant unlimited wishes to any that feed it the leaves of a special plant it has long become addicted to.
Unable to feed itself as it can barely move the creature offers those that come across it these unlimited wishes, but the cost is high as feeding the Zalkor also removes a person's soul, effectively trapping them in a union with the creature for all of eternity.
While Count Abyss was the face of the empire, the Zalkor could be considered the power behind the throne as all wishes bestowed upon Abyss were at the will of the Zalkor - likewise without Count Abyss to feed it the Zalkor would be doomed to starve to death.
This dependency on each other would ultimately be the means to stop the two villains when Count Abyss was tossed across dimensions, sealed away from the Zalkor, thus presumably sealing both of their demise.