There are a lot of clues that a mutant massacre could happen in the next X-Men movie. Post here all your hints or suggestions on what characters or events in X3 could cause the Mutant Massacre story line for the next movie. We obviously are introduced to Callisto in X3...leader of the Morlocks. Psylocke is in the brotherhood in X3. When the mutant massacre occurs, she joins the X-Men. Angel is introduced in X3 and is captured during the massacre to produce Archangel.