Not much is known about Shen Xorn, except that he is the twin-brother of Xorn and that he has similliar powers to his brother's and an almost identicall iron mask on. Shen Xorn is seen as a passive peacefull man. This is in stark contrast to his brother Xorn would become something much worse while under the influance of an evil entity known as Sublime.
Shen Xorn was created by Chuck Austen and Salvador Larroca and first appeared in X-Men issue 157 (2004). He is not to be mistaken for Xorn, the mutant that impersonated Magneto during the New X-Men story-line.
In Grant Morrison's critically acclaimed and revolutionary New X-Men run, a new character was introduced called Xorn. Xorn was eventually revealed to be the X-Men's greatest foe Magneto who had infiltrated the X-Men and made a complete mockery of Xavier's dream and naivety before launching an enormous attack on New York City. Marvel was unhappy with the portrayal of Magneto, presenting him as blatantly having fell from grace and entirely remorselessly evil, and disliked getting rid of the Xorn character who had proved popular. Immediately after Grant Morrison departed, writers Chris Claremont and Chuck Austen set about retconning what had happened. To this end, Claremont revealed Magneto was alive and Xorn was not Magneto but a delusional imposter, whereas Austen introduced Shen Xorn, Xorn's twin brother, to explain Xorn's status and also fill Marvel's desires of keeping Xorn around.
Major Story Arcs
A Brother Lost
Shen Xorn turned up after the original Xorn was killed by Wolverine. Claiming to be Xorn's twin brother and that his brother was being controlled by Sublime, Shen was taken into the X-Men's care until they could determine the truth. This was confirmed by Emma Frost when she telepathically read his mind. Xorn later saved the X-Men from the Brotherhood of Evil Mutants being led by Exodus by opening his helmet and lets out a black hole from his head. He was later affected by M-Day, thus became depowered.
Return: With Magneto's Uncanny X-Men
Some months after the events of Secret Wars, Shen Xorn is seen again, seemingly with his mutant powers intact, when he is contacted by Magneto. Magneto warns him that a group of mutants known as the Dark Riders hunt for mutant healers, which Shen Xorn is. Shen thanks Magneto for the warning, but wants to remain at peace and stays in the temple where he has lived for some time. It was then that the Dark Riders traced Shen and attacked him. Shen was able to defeat the Riders after which the others flead the scene. So far, Shen Xorn has been in contact with Magneto on a number of ocassions.
The Xorn brothers are leaders of the Celestials and Eternals in the Ultimate Universe.