Rifts: Promise of Power
Extradimensional horrors who control the continent of Atlantis
A Splugorth is a true terror to behold: a massive, quivering blob of flesh, slime, eyes, and tentacles, some of which are covered in suckers or mouths. The creature is easily forty or fifty feet across, and a mere glimpse of its horror can drive weak-willed men to madness.
Little to nothing is known of the Splugorth, save that they are apparently alien monsters from another dimension and that the continent of Atlantis is their playground.