Transformers: Generation 1

T03:C18 - S03:E18 - The Dweller in the Depths

The Quintessons trick the Decepticons into unleashing their monstrous beast, the Dweller deep within Cybertron surface. Awakened from its slumber, the creature targets Autobots and Decepticons alike, turning some of its victims into energy vampires. Now, the Autobots must prevent the beast from draining their home planet of Cybertron of its energy.