The Caller in the Dark

The Caller in the Dark was a creature of an unknown origin that was found under the surface of Makeb, near the location of an ancient abomination Gethul. Gethul was able to exert mind-control over both sentient individuals and non-sentient creatures, as demonstrated when a team led by Jedi Master Adelade uncovered it in 3631 BBY. Though not yet fully awake, Adelade and her followers heard Gethul's "song" and fell under its sway, forming a Cult of Gethul and attempting to fully awaken the creature. Learning of this and fearing that in its full power Gethul could destabilize Makeb's core and obliterate the planet, Eternal Alliance military Admiral Bey'wan Aygo sent a strike team to stop Adelade's plan. After confronting and killing Chief Engineer Penzaren, the team approached and engaged The Caller in the Dark, eventually killing it and somewhat lesseing the mental toll on their minds.

Behind the scenes
The Caller in the Dark appears in Star Wars: The Old Republic: Knights of the Eternal Throne as a bonus boss during the "Destroyer Of Worlds" Uprising.