Katherine "Kitty" Pryde is a mutant with phasing abilities and is able to rise and lower herself through solid objects. She is a student at Xavier's School for Gifted Youngsters. She is from Illinois. Senator Kelly referenced as "the girl who can walk through walls" in congress. Which wasn't nice because he had the wrong idea.
When William Stryker's military forces attacked the X-Mansion, Kitty phased through walls and helped people to escape. Xavierused Kitty to retrieve files from Stryker's office which he presented to the President of the United States.