Plasmus

Plasmus is a villainous monster and an enemy of the Teen Titans.

History
Plasmus is actually a symbiote. While his original form is human, he involuntarily transforms into a large purple ooze monster whenever he is awake. As a result, whenever he is in custody, he is put into a soundproof stasis tank to prevent him from transforming.

Plasmus first appeared in the series when Cinderblock stole his stasis tank from prison so he could be reawakened and used as a decoy for Slade's purposes, but the Titans managed to apprehend him again shortly after his deployment. In a later conflict, the mixing of Plasmus' temporarily disrupted body structure with raw sewage transformed him into a more inhuman version, giving him multiple green eyes and making him capable of spitting acid. It is not known how the battle with the Teen Titans against Plasmus ended, possibly either the Titans defeated him without Starfire's aid or Plasmus was scared away by Starfire's appearance.

Later, Plasmus was re-recruited by Slade and Terra and ordered to distract Cyborg and Beast Boy from saving the rest of the Titans. After Terra failed to defeat the Titans, Plasmus was fused with Cinderblock and Overload to form the creature Ternion, combining their powers into a more frightful and powerful version. Ternion proceeded to attack the Titans, but was eventually defeated; Plasmus, along with Cinderblock and Overload, were diffused and went their separate ways. Plasmus shows up again to menace the Titans on their "last day" before Trigon's arrival, where he was defeated single-handedly by Raven, who projected her astral form into Plasmus' mind, rendering him unconscious. Plasmus later resurfaced again, this time as a recruit the Brotherhood of Evil. When the Brotherhood carried out its plans to eliminate young superheroes all around the Earth, Plasmus was sent in Trident's company into the deep sea, where they captured Aqualad and Tramm. When Beast Boy and his Titans team arrived at the Brotherhood's base for battle, Plasmus joined the fight. He managed to catch Beast Boy in the fray, but again Raven used her astral self to render him unconscious, defeating him.

Power and Abilities
Plasmus' primary power is superhuman strength. As a creature composed of ooze and with no solid skeletal structure, Plasmus is able to both withstand and regenerate from a vast amount of physical damage, and to execute limited shape-changing and limb-stretching. In combat, he attacks distant enemies either by elongating his limbs (or creating additional ones) to whip or grapple them, or he spits slime to bludgeon and entrap them. In his second incarnation, Plasmus also became capable of spitting acid. Plasmus is also purple and green.