Theresa Cassidy

Siryn is a mutant.

History
Theresa Cassidy 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.

Trivia

 * Her name (along with her father's, Banshee) also appears on a list of names Mystique scrolls through on Stryker's computer while looking for Magneto's file.

Appearances/Actors

 * Canon (2 films)
 * X2: X-Men United - Shauna Kain
 * X-Men: The Last Stand - Shauna Kain