Alias: Banshee
Name: Sean Cassidy
Team Affiliation: X-Men, Interpool Agent, NYPD, Co-Headmaster at Mass. Academy,Co-Leader of Generation X
Powers: Mutant Enhanced Vocal Chords that can bend steel enable him to fly  or gently put you to sleep.
Family: Theresa Cassidy (daughter, Syrin of X-Force), Black Tom Cassidy (cousin).
First Seen: Uncanny X-Men # 28

     Sean Cassidy was born in Ireland. In his mid 20's he joined Interpol, an anti-terrorist group. His wife, Maeve, died leaving a baby daughter named Theresa. Seans rival cousin, Tom (Black Tom), took custody of the baby, keeping Sean in the dark about her.
       Sean later joined the NYPD for a few years and then became involved with a mutant terrorists, Factor Three, and was being used against his will. He joined the X-Men after they saved him (numerous times).
       He found out that his daughter was Theresa and gained custody of her when Tom was sent to prison.
       After falling in love with Moira MacTaggart, Cassidy became less and less involved with the X-Men until he, The White Queen, Jubilee, Sabretooth, and the "Next Generation" of mutants, had a run in with the Phalanx ( see Foes, Phalanx). After Blink (a young female mutant with the power to "Blink" things out of existance) gave her life to destroy the Phalanx, Sean and the White Queen became the headmasters of Xaviers School for Gifted Youngsters and the Leaders of GENERATION X.