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Sean Cassidy (Earth-616): Misc


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Up to date as of February 09, 2010

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Real Name
Current Alias

Irish, Agent #215-66, presumably other undercover aliases



Formerly X-Corps, Generation X, X-Men, Factor Three, NYPD, Interpol, Muir Islanders

Maeve Rourke Cassidy (wife, deceased), Theresa Rourke Cassidy (daughter), Black Tom Cassidy (cousin), Victoria "Tori" Donnely (Maeve's cousin), Liam Cassidy (ancestor, deceased)



6' 0"

170 lbs (77 kg)



Marital Status

Adventurer; former paramilitary commander, academic headmaster, gentleman of leisure, carnival barker, subversive, criminal, freelance operative, NYPD detective, Interpol inspector

Sean is a mutant, born with his amazing abilities that developed during puberty.

Place of Birth
Cassidy Keep, County Mayo, Ireland

First appearance
Appearance of Death

X-Men #28
(January, 1967)
X-Men: Deadly Genesis #3
(March, 2006)




Early Years

Sean Cassidy was born as the heir to the castle and estate of Cassidy Keep, Ireland, as well as a small fortune. After graduating from Trinity College, Dublin, with the degree of Bachelor of Science, Cassidy became a detective at Interpol, the international law enforcement organization. By the time he married Maeve Rourke, Cassidy had risen to the rank of Inspector at Interpol. Although Cassidy had discovered his mutant powers in his adolescence, he kept them secret, even from the rest of Interpol.

Banshee as civilian

However, Cassidy's powers were known to his disreputable cousin Black Tom Cassidy, who had discovered that he himself was a superhumanly powerful mutant. Sean and Black Tom had long been rivals, especially over the love of Maeve Rourke, before she ultimately married Sean.

Sean Cassidy was assigned by Interpol to a top secret mission which required that he stay out of touch with his family for a considerable amount of time. When he left on the mission, Maeve was in her first month of pregnancy, although neither Tom nor Maeve knew it at the time. Their daughter, Theresa, was born during Sean's absence. Maeve took the infant Theresa with her on a visit to her relatives in Armagh in Northern Ireland. While she was there, Maeve, an innocent bystander, was killed by an explosion caused by terrorists. No trace of Theresa was found by the authorities, and they and Maeve's relatives assumed that Theresa had also been killed in the explosion. In fact, however, Black Tom Cassidy had been present at the scene of the explosion and had secretly carried Theresa off with him. Black Tom suspected that Theresa might develop superhuman mutant powers as she grew older, and therefore he intended to raise her secretly so that he might exploit her powers himself.

On returning from his mission, Sean Cassidy was informed that his wife was dead. Those who knew that Theresa had been born decided not to inform Sean Cassidy that Maeve had had a daughter in order to spare him further grief. At first Cassidy attempted to escape his despair over this news by throwing himself into his work at Interpol. Eventually, however, the still melancholy Cassidy left Interpol to become a freelance operative, and as time went on, he found himself engaged in criminal activities.

Factor Three

The legal authorities never discovered that Cassidy was guilty of crimes, but the mutant known as the Changeling did, thanks to the technology of the subversive organization of superhumanly powerful mutants and their underlings 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 Changeling and his superior, the so-called Mutant Master, agreed that Cassidy's powers and knowledge of the workings of law enforcement agencies were too valuable for Factor Three to lose, and so they sent their agents to capture Cassidy. Factor Three placed a headband containing explosives 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. Furthermore, Factor Three put Cassidy, who went by the code name of Banshee, under the supervision of one of their trusted human agents, the Ogre. The Banshee thus felt forced to obey Factor Three's commands, and, accompanied by the Ogre, performed various criminal missions for the organization.

While in New York City on a mission for Factor Three, the Banshee clashed with the original X-Men, who captured both him and the Ogre. The X-Men's leader, Professor Charles Xavier, used a psionic "mental bolt" on the Banshee's headband which prevented the detonation mechanism from functioning so that the Banshee could remove it. Once freed of the headband, the Banshee told the X-Men all that he knew about Factor Three. Later, the Banshee discovered Factor Three's secret European headquarters, only to be recaptured. But the Banshee participated in the X-Men's battle with the Mutant Master, and it was the Banshee's powers which exposed the Mutant Master as an extraterrestrial.



The Banshee returned to an honest life, and time passed without major incident for him, except for his brief captivities by the Sentinels, and by the second Secret Empire. Professor Xavier later invited the Banshee to join the X-Men when he was recruiting new members to battle the menace of Krakoa. After most of the original team left for a time, Cassidy, along with fellow new recruits Storm, Colossus, Wolverine, and Nightcrawler, stayed as members of the new X-Men. He remained with the X-Men for a time, and encountered adversaries such as the N'Garai, Magneto, the Juggernaut, and his own cousin Black Tom. It was during this time that he met Xavier's silent partner, the Scots geneticist Moira MacTaggart. Cassidy and MacTaggart soon fell in love, but while Cassidy was based at Xavier's mansion, MacTaggart was based at her mutant research center on Muir Island off the coast of Scotland.

While in Japan the X-Men found themselves in battle with Moses Magnum, a criminal mastermind who had been endowed with psionic power to cause earthquakes. Magnum unleashed tremendous psionic energy in an attempt to create seismic waves great enough to cause a chain reaction that would destroy Japan. The Banshee simultaneously used his powers to create waves of vibratory force that would cancel out the waves of force that Magnum was creating. The Banshee succeeded to the extent that only small uninhabited islands in the vicinity of Magnum's base were destroyed. However, the tremendous strain that the Banshee had placed upon his powers in performing this heroic feat seriously damaged his vocal cords. Cassidy soon regained his ability to speak, but his superhuman sonic powers, which were dependent on his vocal cords, appeared to have been destroyed.

Cassidy accompanied the X-Men to Muir Island where they battled the menace of Proteus, Moira MacTaggart's mutant son, who at one point took his mother prisoner. Proteus was defeated, and the experience of seeing the woman he loved in danger made Cassidy realize that he wanted to stay by her side. Therefore, Cassidy retired from the X-Men, and he and Moira MacTaggart divided their time between Cassidy Keep and Muir Island. Cassidy briefly returned to aid the X-Men against operatives of Arcade during an emergency situation when most of the X-Men were simultaneously engaged in conflict with an android which Doctor Doom had created in his own image.

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.

Generation X

After rejoining the X-Men as an active member, Banshee suddenly realized the Phalanx's kidnapping of the X-Men. He and Emma Frost worked to save some young mutants targeted by the Phalanx. Banshee later became the co-head master of the Massachusetts branch of the Xavier institute along with Emma Frost, the branch that housed Generation X.

Generation X disbanded after Chamber's graduation, shortly after the death of Sean's lover, Moira MacTaggart. Sean became inactive, until He turned back to his alcoholism for a brief period, and then his bitterness towards the mutants who were like those who killed her got to him.


Sean founded X-Corp, a superhuman militia organization that used primarily mind-controlled formerly terrorist mutants to protect mutant kind at large. Mystique infiltrated the organization in disguise, and slit Cassidy's throat. Luckily, he managed to capture Mystique by releasing Abyss, a mutant who could open an other-dimensional portal.

He did little more without his powers for a long time, until he was asked by the X-Men to go to Muir Island after M-day to look for any notes that might help find Professor X. Sean uncovered some startling information, and quickly arranged a flight to Westchester.

He was supposed to meet Nightcrawler and Wolverine, but noticed that the Blackbird seemed to be heading towards the plane on a collision course. He quickly used his powers to fly and attempted to use his sonic scream to stop the plane from hurting the passengers, Sadly, it was not enough to stop the Blackbird and it rammed into him as well as the plane filled with innocent passengers. Banshee's body was found by Kurt and Logan. When the X-Men were blamed for the situation early on, Emma Frost told O.N.E. that the attack also killed the X-Men's best friend.

Cyclops delivered the news of Banshee's death to his daughter, Siryn.[1] Siryn was given a video tape that Banshee had made for the purpose of delivering a message to his daughter when he died. In the message, Banshee stated that he felt he had done more good than bad in his life, and that he hoped St. Peter would allow him entrance into Heaven. He expressed the hope that he would there be re-united with Siryn's mother. Siryn refused to believe that Banshee was really dead, citing all of the X-Men in the past who have been presumed dead but later returned. Sean willed Siryn Cassidy Keep, as well as his pipe.

He was buried at the Xavier Institute, along with the empty graves of Sway and Petra Kristensen. Charles Xavier, Quicksilver and Siryn were notable guests at the funeral. Banshee was seen in Erebus by Hercules along with many other deceased beings, gambling for his soul. Later, Banshee, along with many other deceased mutants, was been resurrected by Selene and Eli Bard with the Transmode virus.

Powers and Abilities


Banshee is a Alpha-Level mutant.

Audiokinesis: he creates powerful sonic waves with his voice with which he can achieve various effects, often with the assistance of limited psionic abilities which function only in unison with his sonic power.

  • Sonic Scream: ability to shatter solid objects with a sonic scream
  • Flight: ability to fly at subsonic speeds by using his voice to propel him through the air.
  • Sonar: can use his sonic powers as a form of sonar (Sound Navigation and Ranging). By sending out a precise, pure note and listening to the returning, altered wavefront of the note, he can evaluate his surroundings in total darkness with varying degrees of resolution.
  • Sonic Shield: can tighten sound waves around himself or others near him, making a barrier against outside attack.
  • Vocal Disorientation: ability to change someone’s balance, by affecting their equilibrium using his sonic scream
  • Vocal Trance: ability to subtly influence people's subconscious mind by changing the tones and vibrations of his voice using sonics
  • Vocal Unconsciousness: ability to affect the fluid in someone’s ear causing the person to go unconscious.
  • Sound Immunity: Banshee's hearing and equilibrium are unaffected by his power or other similar abilities.
Superhuman Vocal Stamina: possesses superhuman stamina in his lungs, throat, and vocal cords


A gifted detective, seasoned undercover operative, and unarmed combatant, Sean was also well-versed in combat strategy and tactics. He was an excellent marksman, amateur machinesmith, educator, organizer and lobbyist. His interests included American country music and playing the piano.

Strength level

Sean Cassidy possesses the normal human strength of a man of his age, height, and weight who engages in moderate regular exercise.


His vocal cords are susceptible to injury from excessive strain in using sonic powers. He has also survived normally fatal throat wounds at the cost of his sonic powers temporarily.



Flight under his own power; X-Men Blackbird, X-Men Stratojet.


Conventional firearms, explosive "micro-bombs".


Banshee had dealings with Magneto, Omega Red, and Deadpool when he was an agent of Interpol.


  • When originally created, Roy Thomas and Werner Roth had the Banshee as a female, but Stan Lee told them that female villians are not as popular as male, and she was changed into a male. Roy noted that the way Siryn looked, is what Banshee was originally going to look like.
  • Banshee was also immune to his cousin Black Tom's energy blasts.
  • The "ribbons" on Banshee's costume (a visual trademark of the character) aided him in his flight.

Appearances in Other Media

  • Banshee appeared in the X-Men Animated Series. He also fought Black Tom Cassidy in the Phoenix Saga.
  • Banshee also made an appearance in the Fox TV movie Generation X. He was portrayed by Jeremy Ratchford alongside Finola Hughes. While multiple sources have listed Jeremy Ratchford as the voice of Banshee in the X-Men Animated Series, he has said in interviews that he did not provide Banshee's voice in the cartoon.
  • X-Men Legends


Discover and Discuss

  1. X-Factor volume 3 #7

This article uses material from the "Sean Cassidy (Earth-616)" article on the Marvel Database wiki at Wikia and is licensed under the Creative Commons Attribution-Share Alike License.


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