X-Men Movieverse Wiki
File:Terry Cassidy.jpg
Theresa Rourke Cassidy
Codename: Siryn
Joined Since Inception
Gender Female
Age format=y}}
Birth July 7, 1985
Mutation Sonic Manipulation
Height 5'5"
Hair Red
Eyes Green
Skin Fair, with a tendency to freckle on her face.
Markings Small colorful tattoo about the size of a half-dollar of an enclosed circular Celtic cross on left hip. Three parallel scar lines running along left shoulder blade, very faint.
Associations Xavier's School
Communication To/From Regarding

Terry Cassidy is the daughter of Sean Cassidy and Maeve Rourke, born in Ireland and raised by her uncle, Tom Cassidy, in a life of small-time cons. She attended Xavier's School and after graduation spent time abroad in schooling and working with various police organizations as a sometimes consultant. She was recruited into the trial run of X-Factor, and serves as the Head of Intelligence.


Associates degree with a focus in psychology and law enforcement. The credits have been gained across a number of schools though, so she has more classes than an associates would entail, just not enough to gain a BA from any one school.


Prior to X-Factor, Terry was making a sporadic living working as a consultant for various European law enforcement and private sector agencies, dealing mainly with mutant issues and policies.


Notable Public Information[]

Terry is the daughter of Sean Cassidy, a notable among the mutant and international police community. She is an Xavier's School alum.  


Siryn can manipulate her vocal chords beyond human limits, effectively mastering sound vibrations that allow her to punch small holes in most materials (reliable, high frequency) to resonate damage to large structures (unreliable, low frequency). In between these two extremes are less powerful sound wave frequencies that can cause humans to experience nausea or discomfort (reliable). She can use her voice as a sonar device to map out her surroundings. As a side affect of her vocal control, she can also use her voice to create a hypnotic-like state in others (effect variable) wherein they are susceptible to suggestions, like mythical Sirens.


Terry has an amalgamation of skills gathered from natural ability and an eclectic education, starting with her time under her uncle’s tutelage, including pickpocketing skills which are still on the rusty side from disuse. She’s good at reading people and understanding motivations as a result of the early exposure to con games and subsequent study of psychology.

She’s competent with computers, and knows enough basic programming to help manipulate databases and find her way around a lot of programs fairly easily. She’s also a puzzle solver with a good eye for patterns.

She knows tourist French, Italian, and German.

Personality Profile[]

Dedicated, loyal, stubborn. Terry typifies a number of Irish stereotypes, including the one about the temper. She's quick to flare and quick to burn out, and though she can carry a grudge like no one's business, it is usually reserved for pretty big injuries. She has the tendency to take things personally and carries a huge sense of responsibility for her teamates and the organization. She cultivates the image of the occassionally ditzy college co-ed, but is in truth a fiercely devoted professional.



Basic Agent Certifications

Planning and Organization

Covert Skills



In Progress[]

Close-Quarters Combat

  • Unarmed Hand-to-Hand


  • Boats (Sail)




Terry as a turtle.

It became obvious, especially after the events of Antique Lands that Terry's drinking was on the upswing following her break up with Remy LeBeau. Noted and confronted first by Eshana, Terry went through withdrawal symptoms while captured by the La Morada and is currently held in suspicion by the Antique Lands team lead, Alden. She has since tapered off public consumption and appears to have settled back into something a little more even-keeled after her reconciliation with Remy.

Mission History[]