Gethul

Gethul was a creature of an unknown origin that was hibernating under the surface of Makeb for millenia preceeding the Galactic War. No record of the creature existed before its discovery in 3631 BBY, although Doctor Juvard Illip Oggurobb was later able to find traces organic matter unique to Belsavis inside its digestive tract, speculating that the creature originated there. Oggurobb also theorized that Gethul was a genetic experiment by the Rakata, as it contained their genetic markers, along with those of Rathtar, Dianoga and dozens of other species. Gethul also possessed an immense mind control power suggesting Force-sensitivity, as demonstrated when a team led by Jedi Master Adelade uncovered it based on intel from am anonymous source. 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. The team was engaged by the cultists of Gethul, as well as Chief Engineer Penzaren and local wildlife, which Adelade and Gethul were also able to control. Eventually they reached Adelade herself and after defeating her in combat, detonated the D-5X probe droid loaded with explosives inside Gethul's maw, killing the abomination and stopping its threat.

Behind the scenes
Gethul appears in Star Wars: The Old Republic: Knights of the Eternal Throne during the "Destroyer Of Worlds" Uprising.