Kitty Pryde is a super-hero who has been affiliated with the X-Men, Excalibre, the New Mutants and SHIELD . Her super-powers include an ability to "phase" through objects and to walk on air, as well as a near superhuman ability to understand electronics.
She was, I believe, one of the first characters developed by Chris Claremont during his famous run on the X-Men. She was (for a comic book at least), a well-rounded young female character in an era when comic books were still full of men with big muscles, and women with big breasts, in spandex.
Kitty Pryde came from a upper middle class Jewish home in Chicago, Illinois. When she was 13, she begin developing phasing episodes. Charles Xavier, aka Professor X, found her and invited her back to his school. She quickly became a member of the X-men, although there was some doubt in Xavier's mind whether he should subject someone so young to so much danger. but Kitty Pryde, who took the code name "ShadowCat" proved herself capable of handling the situation.
In what I think of one of the many charming relationships that Claremont developed amongst his characters, the young, innocent Kitty was befriended by the gruff, somewhat cynical Wolverine, who took Kitty to Japan in the Kitty Pryde and Wolverine mini-series. He also trained her in the way of the Ninja.
Other then Wolverine, some of Kitty's other good friends in the X-Men were Colossus, the Russian who could turn his body into steel, and Colossus younger sister, Majik, who was both a teleporter and an extra-dimensional sorceress. And, of course, her pet dragon, Lockheed.
Much of Kitty's later life, including her move to England, her joining up with SHIELD, and her ceasing to be quite so cute and innocent, happened after I stopped reading comics, so that it might be best for someone else to fill in these details.