|“|| I’m going to be... Banshee|
Why do you want to be named after a wailing spirit?
You may want to cover your ears...
|~ Banshee and Beast, with Cassidy telling his teammates on using his ability.|
Sean Cassidy, also known as Banshee, is a character from the 2011 film "X-Men: First Class". He is a mutant with the ability to create powerful sonic waves with his voice, and becomes a member of Division X and the X-Men to stop the Hellfire Club.
He is portrayed by Caleb Landry Jones.
X-Men: First Class
After the Hellfire Club tried to recruit them, Sean and the others relocated to Xavier's mansion where they began training to defeat Shaw. Xavier taught him how to control his ability and use it to fly by using a harness developed by Hank McCoy.
Banshee witnessed Erik come from the sub with Sebastian Shaw's corpse, and later saw him attempt to kill the American and Soviet soldiers with missiles. Banshee and the others attempt to help Charles when he attacks Erik, but the latter stops them by using his powers. After Erik leaves with Mystique, Azazel, Angel and Riptide, Banshee helps Charles as he has become disabled.
X-Men: Days of Future Past
Some time later but prior to 1973 he was killed, likely as part of Bolivar Trask's experiments on mutants.