200px-Theresa Rourke (Earth-10005)-1-
Real Name Theresa Rourke Cassidy
Current Alias Siryn
Aliases Theresa Rourke
Gender Female
Species Mutant
Alignment Good
Relatives Sean Cassidy (father)
Occupation Xavier Institute student
Affiliation X-Men
Location X-Mansion
Status Alive
First appearance X2: X-Men United
Last appearance X-Men: The Last Stand
Portrayed by Shauna Kain


X-Men filmsEdit

Theresa Cassidy is a mutant who can emit a high-pitch sonic scream. She is a student at Xavier's School for Gifted Youngsters.

During William Stryker's attack on the mansion, her scream alerted the rest of the school that they were under attack. She was captured, but was rescued by Colossus.

Powers and AbilitiesEdit


Sonic Scream: She can scream very loudly, and at a high-pitch.



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