Theresa Rourke Cassidy
Private detective; former adventurer, research assistant, criminal, student
Siryn possesses sonic powers similar to those of her father Banshee, although she is able to use her powers in ways that he apparently cannot. She possesses an enhanced sense of hearing and sonar. While screaming Siryn is able to fly, most likely around Mach 1. Siryn has especially potent sonic attacks. She can shatter objects, project sonic force, or cause pain and unconsciousness. Siryn is able to subtly influence and control others with her sonics as well as cause them to enter a trancelike state. Siryn has recently shown the ability to also block out others from hearing sounds so that she can secretly deliver messages.
While still a young teen, Theresa accompanied Black Tom and his then-partner, the Juggernaut, to San Francisco to assist him in his crimes. Here, employing the name Siryn, Theresa aided them in a theft of vibranium, and battled the original Spider-Woman and several of the X-Men. This conflict ended in Black Tom's temporary capture. While in custody, Black Tom relieved Theresa of responsibility for her crimes and wrote a letter to Sean explaining who she was. The X-Men brought Theresa back to their headquarters, where she was joyfully reunited with her father. (To learn about the above characters, click on their highlighted names. Note: Beware of the skin-tight outfit worn by Spider-Woman on her bio page. One of the first outfits she wore is shown in the third picture posted.)
Theresa soon moved to Muir Island, home of the research laboratories of Dr. Moira MacTaggert. While living back on the island, Siryn started a romantic relationship with the mutant known as Jamie Madrox (aka Multiple Man). However, this version of Multiple Man turned out to be one of his many duplicates and not the original Multiple Man, leading to the end of the relationship. (Click on the highlighted names above to learn more about the characters/place.)
Later, Siryn became a core member, and even a field leader, of the X-Force (a paramilitary superhero team). In the X-Force, Siryn began a romantic relationship with Deadpool. However, in the end, Siryn became overwhelmed with balancing her duties with X-Force and the demands of Deadpool's somewhat faulty sanity. Later on, she leaves after Feral (a former teammate turned villain) slashes her throat. This injury destroyed Siryn's vocal cords and made her temporarily mute and powerless. But, thanks to Deadpool stealing a sample of Wolverine's blood, Siryn was able to fully heal from her vocal cord injuries. (To learn about the above characters, click on their highlighted names. Siryn wore different outfits during her time in the X-Force. Two of these can be seen in the first and fourth picture posted. )
Soon after, Siryn joined up with X-Corporation where she was reunited with old friends such as Multiple Man, Rictor, and Cannonball. However, their first mission did not go so well and Siryn leaves the group. (To learn about the above characters and/or team, click on their highlighted names above.)
After that, Siryn joined up with Multiple Man's X-Factor Investigations in Mutant Town. During her time with X-Factor, her father was killed while trying to save an airplane full of innocent civilians. Although, he was confirmed to be dead by Wolverine and Nightcrawler, she is in a state of denial since many X-Men have died and then later miraculously been found alive and well. However, after some time, Siryn came to terms with her father's death and has recently taken her deceased father's codename as her own and begins calling herself "Banshee" in honor of his memory. (To learn about the above highlighted team/place/person, click on their highlighted names above. Note: Beware of revealing outfits worn by some on the X-Factor bio page.) The last picture posted is of Siryn in her uniform during her time in the X-Factor.)
To learn more about Siryn/Banshee, click on the following link, http://marvel.com/universe/Siryn.
Siryn is in both, X2 and X-Men: The Last Stand. In X2, when William Stryker's forces invade the X-Mansion, Siryn is the girl that screams really loud that makes everyone in the mansion have to cover their ears. We also see her briefly in X-Men: The Last Stand.