Banshee (superhero)Banshee (also known as Sean Cassidy) is a mutant in the Marvel Universe and a member of the X-Men. Born the heir to a small fortune and a castle in Cassidy Keep, Ireland, he discovered his mutant powers in his teens. His ability is the creation of powerful sonic waves with his voice. He can use the sound he generates to propel himself through the air at the speed of sound, to shatter solid objects, to place people in a temporary trance, or to cause people to fall unconscious. His throat, vocal cords, and lungs are superhumanly resistant to strain, but they are susceptible to injury from excessive use of his sonic powers.
In his youth, he married Maeve Rourke, and took a job at Interpol, the international law enforcement organization. While Sean was away on a long mission, his wife discovered she was pregnant and gave birth to their daugheter, Theresa Cassidy. Then, with Sean still on assignment and unable to have heard of his daughters' birth, Maeve was killed by a terrorist bomb on a visit to relatives in Northern Ireland. Sean's disreputable cousin, Black Tom Cassidy, rescued Theresa, secretly planning to raise her himself. When Sean returned, he was devestated to hear of Maeve's death. Those who knew that Theresa had been born decided not to tell Sean that he had had a daughter in order to spare him further grief. Cassidy left Interpol to become a freelance operative, and as time went on, he found himself engaged in criminal activities. A mutant called the Changeling discovered him, thanks to the technology of the criminal organization of mutants known as Factor Three. The Changeling contacted Cassidy, whom Factor Three's technology had also identified as a superhumanly powerful mutant, and invited him to join the organization. Cassidy was appalled upon learning of Factor Three's goals and adamantly refused. However the members of Factor Three agreed that Cassidy's powers and knowledge of the workings of law enforcement agencies were too valuable for them to lose, and so they sent their agents to capture Cassidy. Factor Three had a headband containing explosives placed around Cassidy's head. If Cassidy defied their orders, the headband could be detonated by remote control; it would also detonate if Cassidy attempted to remove the headband himself. The Banshee, which was the codename he took at this point, felt forced to obey Factor Three's commands, and performed various criminal missions for the organization.
On a mission in New York City, Banshee came into contact with the original X-Men. Professor Xavier was able to use his extraordinary mental abilities to disarm the headband and remove it, thus allowing the Banshee to tell the X-Men all that he knew about Factor Three. After a period of time, Sean joined the X-Men, where he met and fell in love with the X-Men's ally, Dr. Moria MacTaggart. Later, the X-Men battled Black Tom Cassidy, his partner the Juggernaut, and Theresa, who had developed sonic powers of her own, which she used under the alias of Siryn. Theresa felt obliged by her duty toward Black Tom, the man who had raised her (and whom she called "uncle" out of respect, although they are actually cousins), to assist him in his crimes. After they were defeated by the X-Men, Black Tom gave Theresa a letter to Sean, explaining that she was his daughter. Sean and Theresa were joyfully united at Xavier's mansion.
Banshee is now the co-headmaster at the Massachusetts Academy, where he teaches the young mutants of Generation X in the use of their powers alongside Emma Frost.
For information on the creature of Irish mythology after which Sean is named, see Banshee.