X-MEN: Generation X
An Irish mutant, Banshee possesses a “sonic scream,” capable of harming enemies’ auditory systems and causing physical vibrations. He is named after the banshee, a legendary ghost from Irish mythology, said to possess a powerful cry.
Sean Cassidy was the heir of Ireland’s Cassidy Keep and estates, and began as a member of Interpol – until his wife was killed in an explosion. Sean later found himself engaged in criminal activities and joined the subversive organization of superhumanly powerful mutants, known as Factor Three, where he used his mutant ability of Audiokinesis to terrorize and encountered the X-Men. Professor Xavier succeeded in releasing Factor Three’s hold on Sean and, after his original team was captured, Sean joined the X-Men. At that time Sean was a decade older than most of the X-Men and had only a relatively short tenure as a full-time X-Man. Sean later met Prof. Xavier’s silent partner, the Scottish geneticist Dr. Moira MacTaggert, and soon fell in love.
After leaving the X-Men, Sean was asked to guide the new generation of X-Men, Generation X, with the former villain, Emma Frost.