published by Marvel Comics
appeared in X-Men #28
Sean Cassidy was born the heir to Cassidy Keep in Ireland where
he was raised. His position with in his family along with his
romance of a woman named Maeve Rourke earned Cassidy the
emnity of his cousin, Thomas Cassidy. The two competed for
Maeve's affection, which was won by Sean.
During his teens, Sean discovered that he was in fact a mutant with
the ability to create special effects when he screamed. The sound
waves that Sean produced allowed him to fly, to project them in
a tight area as a weapon, and to knock people unconcious. Sean kept his
abilities secret from all of his family and even his employers at
Sean and Maeve were married, while Sean served as an inspector within
the intelligence agency Interpol. While Sean was away on an
extended mission that required him to not be in contact with his
family, Maeve gave birth to their daughter. Soon after, Maeve
was caught in a terrorist bombing and killed. Her relatives believed
that Theresa, the daughter, had also been killed. In fact, she
had been saved by Sean's cousin, Thomas, now known as Black Tom
who raised the child. Sean returned to find that his wife was dead,
and his relatives did not tell him of his daughter to save him further
Sean continued to serve in Interpol for a while, eventually retiring.
He worked as a freelance operative for a time, eventually findng himself
on the wrong side of the law. He was never caught for his crimes though
he did clash during this time with the mutant group, the X-Men. Sean
had begun to use his abilities while calling himself Banshee after
the legendary creature. Cassidy decided to go straight and quit being
a criminal, but was forced for a time to work with the criminal group
Factor Three, when they captured him and outfitted him with a
headband containing explosives that they would use if he did not obey.
Banshee was helped by the X-Men who help him get free of the
headband and then he helped them defeat Factor Three.
Banshee dropped off the scene for many years until he was contacted
by Charles Xavier after his students disappeared. Gathering with
a new group of recruits, Banshee and the others rescued the original
X-Men from the clutches of Krakoa, the Living Island. After this,
the new recruits decided to continue on as X-Men.
During this time, Cassidy met and fell in love with Charles Xavier's
friend, Moira MacTaggert. MacTaggert worked with the X-Men for a
time, but later returned to her research station on Muir Island off
the coast of Scotland.
A series of adventures brought X-Men to Japan and pitted them
against the villain Moses Magnum. Magnum had constructed a
sonic cannon and threatened to use it to sink a number of islands
in the Japna chain if he was not paid a ransom. The X-Men engaged
him in battle, but not before he could set off his device. Banshee
used his mutant powers to match the cannon with opposing sonic waves
cancelling out the destructive power of the cannon. In doing so,
Banshee pressed his abilites beyond their limits and seemingly
damaged his vocal cords. After they healed, Banshee was able to
speak, but maintaining his sonic scream was beyond his abilities.
Banshee retired to Muir Island and spent time with MacTaggert.
He did come out of retirement for a short time to lead a group
of heroes to rescue relatives of the X-Men from the clutches of
the assassin Arcade. During this time, Banshee also learned
of the existance of his daughter Theresa who had gained powers
similar to his and had adopted the name Syrin.
With the help of the Morlock healer, Cassidy's ability to use
his sonic scream was returned to him so that he could aid in the
defense of Muir Island from an attack by a group of cyborg warriors
known as the Reavers. Cassidy returned to X-Men for a time and
later became the headmaster of the Massachusetts Academy, training
a new generation of mutants who later became known as Generation X
with the help of former White Queen of the Hellfire Club,