Banshee

Sean Cassidy, known as Banshee, is a Marvel Comics mutant superhero created by Roy Thomas and Werner Roth. He first appeared in X-Men #28 (1967) as a reluctant villain before becoming a long-standing member of the X-Men.

Born into an ancient Irish clan, Sean grew up at Cassidy Keep, a castle in County Mayo, Ireland. He served as an Interpol agent and NYPD officer before his mutant abilities drew the attention of the villainous organization Factor Three, which forced him into service using an explosive headband. After the X-Men freed him, Banshee joined Professor Xavier's second generation of X-Men alongside Storm, Wolverine, Colossus, and Nightcrawler.

Banshee's mutant power is a devastating sonic scream capable of shattering steel, disorienting opponents, and enabling him to fly by riding his own sound waves. He later co-founded the Massachusetts Academy with Emma Frost to train the next generation of mutants in Generation X. His daughter Theresa, known as Siryn, inherited his sonic abilities and carried on the Cassidy legacy.