Nergill

King Nergill rules Sub-Atlantica, a hidden kingdom of water-breathing fishmen. Their relationship to humanity proper is uncertain.

Cartoon continuity
When the Decepticons arrived at Sub-Atlantica, Nergill greeted them, but Starscream, being Starscream, fired on the Sub-Atlanticans. After Megatron smoothed things over, Nergill showed him his energy storehouses, which were derived from geothermal energy. Megatron and Nergill negotiated a deal in which the Sub-Atlanticans would provide the Decepticons with energy. In turn, the Decepticons would provide Cybertronian technology that would allow Sub-Atlantica to breach the surface and make war on the land dwellers. When the Autobots came to investigate, the Sub-Atlanticans captured Wheeljack. Nergill studied his design to develop the Magnetic Dysfunction Ray, which would disrupt Autobots. After Starscream surprised him, Nergill found it was less effective against Decepticons, but still useful enough.

Heading to Washington, D.C., Nergill subdued Optimus Prime and the Autobots, but refrained from attacking the Decepticons just yet. When Grimlock battled Megatron, Nergill decided to zap them both, but Starscream stole the ray gun, which was subsequently destroyed by Grimlock. Nergill and Megatron ordered their troops to return to Sub-Atlantica.

When Megatron questioned him about the attack on Starscream, the Autobots arrived, intent on finishing the job. As the Dinobots tore through the city, Nergill decided to destroy the city before they could. Throwing a detonator into the energy stockpiles, he caused Sub-Atlantica to self-destruct. Nergill was taken away by the Autobots, but he escaped from them in the chaos of Sub-Atlantica's destruction.

Trivia

 * The name "Nergill" was coined by Gary Owens.