When were the X-Men first introduced by Marvel?
X-Men
1963
Within the Marvel Universe, the X-Men are widely regarded to have been named after Professor Xavier himself. The original explanation for the name, as provided by Xavier in The X-Men #1 (1963), is that mutants "possess an extra power ... one which ordinary humans do not!! That is why I call my students ... X-Men, for EX-tra power!"[4]