Plasma

Plasma is a giant being of pure energy that appeared in Sonic the Comic. He claims to be the "Master of Electrons!" (According to an editorial comment, he is also the master of positive ions, but he never talks about it.) His "body" looks like crackling white fire, and he has two red eyes.

In fact, Plasma is not a person at all, but a focused energy field that is controlled by his "sidekick", Arnem Abacus.

Plasma was an idea of Richard Elson that was tweaked by Nigel Kitching so that it would work in a story.

History
Doctor Robotnik put Arnem Abacus and Plasma in charge of a district of Metropolis City. When the Freedom Fighters attempted to spring several prisoners from a jail in their area, Abacus and Plasma attempted to stop them.

Sonic appeared to be completely outmatched by Plasma: when Sonic attempted a Spin Attack, he was electrocuted by Plasma's body, and when he attempted a Sonic-cyclone to rip Plasma to pieces, it was completely uneffective and Plasma nonchalantly hit him with an energy blast. However, Plasma was eventually defeated when Amy Rose bashed Abacus on the head and smashed the remote that he used to control Plasma. Plasma's energy field was instantly dissipated, making it seem as though Sonic had successfully defeated him after all. Although Amy and Johnny Lightfoot knew the truth, they allowed Sonic (and everyone else) to believe that he had defeated Plasma.

Plasma (and Arnem Abacus) later reappeared when Robotnik, having obtained godlike reality-warping powers, resurrected several of Sonic's old villains. On seeing Plasma, Sonic remarked that Robotnik was "really scraping the bottom of the barrel now!" The villains were defeated when Sonic hit Commander Brutus with a Spin Attack, knocking him into Plasma's energy field, causing a chain reaction that destroyed all the other villains.