Read more about Changeling at: Wikipedia

Official Site: Marvel

Kevin Sydney is a fictional character that has been a member of the X-Men in comic book stories published by Marvel Comics. Created by writer Roy Thomas and artist Werner Roth, the character first appeared in X-Men #35 (August 1967).

Kevin Sydney first appeared as the Changeling, a mutant shapeshifter. He was a short-lived X-Men adversary who, off-panel, joined Professor X's efforts and died shortly after, making him the first member of the X-Men to die in action.

Later a character named Morph in the 1990s was based upon the earlier character of Changeling. The two remain distinct characters in personality and history.

The first run of appearances happened in 1967–1968 when he appeared in X-Men #37-42. Although dying at the end of this run he was thought to have been seen as a ghost in Excalibur: The Possession (1991) and returned as a zombie in Sensational She-Hulk #34-35 (1991–1992).

Changeling has not been a contender in any CBUB matches.