Changeling

Changeling (voiced by Eric Bauza) is a mutant in the X-Men series. The first of the X-Men to die in action, the Changeling is an enigma. He had the mutant ability to alter his physical appearance, costume and voice to imitate any other human being but his true identity remains unknown. He was second in command of Factor Three, a terrorist organization of mutants bent on world conquest. Banshee was a member of the team at one time. Ultimately, though he aided the X-Men in defeating the conspiracy's leader, who turned out to be an alien being. But then the Changeling was discovered that he was dying from a fatal illness and wished to atone for his sins the Changeling sought out Charles Xavier who had a task for him.