Read more about S'ym at: Wikipedia

Official Site: Marvel Entertainment, LLC

S'ym is a fictional supervillain in the Marvel Comics Universe, a demon of Limbo who served as a frequent enemy and sometimes supporting character in The Uncanny X-Men and The New Mutants. He was created as an homage to independent cartoonist Dave Sim's character Cerebus the Aardvark.

Created by Chris Claremont and Brent Anderson, the character is an homage to Cerebus the Aardvark and his creator, Dave Sim, after Sim featured a villain named "Professor Charles X. Claremont" in early issues of Cerebus. S'ym always referred to himself in the third person ("S'ym thinks this is a bad idea"), a trait shared by Cerebus. S'ym also has the same purple-grey coloration as Cerebus, and looks vaguely like Cerebus (right down to his trademark vest), only taller, more muscular, and with a horn. And, of course, "S'ym" is pronounced the same as "Sim".

Cover art by Tom Mandrake.]] -->S'ym was a minion of Belasco, the ruler of the demonic dimension known as Otherplace or Limbo. S'ym first battled the X-Men when the team were transported to Limbo via teleportation "discs" in their search for 7-year-old Illyana Rasputin, the younger sister of the X-Man Colossus. Because the physical laws of time and space differ between dimensions, Illyana seemingly returned to the X-Men only moments later, but returned as a fourteen-year-old.

During Ilyana's seven years in Limbo Belasco took her as his heir and apprentice, until one day she defeated him, becoming Limbo's new ruler - and S'ym's master - before returning to the X-Men. S'ym made several attempts at challenging Illyana's newfound status as Limbo's ruler. At each turn Illyana defeated S'ym, leaving S'ym to agree to serve Illyana whenever she visited Limbo. Finding a potential way to finally defeat Illyana, S'ym allied himself with the extraterrestrial Magus, allowing himself to be infected with a techno-organic virus). Despite the boost in power, that attempt and a subsequent rebellion failed.

S'ym has not been a contender in any CBUB matches.