This is an image shows Stephen Merchant’s pale skin and bald head, Fox has yet to confirm whether or not Merchant is playing Caliban.
Caliban is a mutant in the Marvel Comics universe. The character, created by Chris Claremont and Dave Cockrum, first appeared in Uncanny X-Men #148 in August 1981.
Within the context of the stories, Caliban has been a member of the Morlocks, the X-Men, X-Force, X-Factor, and the Horsemen of Apocalypse. His mutant ability allows him to sense and track other mutants. He also possesses the ability to channel the emotions of those around him to enhance his strength. His upper limits are unknown