Originally conceived as the antagonist for The Lion, the Witch and the Wardrobe, Jadis proved to be more enduring. Her history is recapped in Book Six of The Chronicles of Narnia, entitled The Magician's Nephew. Hiering form the pagan world of Charn, she was a mystical princess at war with her sister. At some point, the witch learned to use "The Deplorable Word," to traumatically end the conflict. The villainess is let lose in our world and eventually finds her way to the dawn of Narnia. There she enjoys a thousand year rule until her death at the hands of Aslan. There's some speculation that she appeared in The Silver Chair as the Queen of the Underland. While it's commonly discredited by fans, I once worked with a children's book scholar at Barnes and Noble's who claimed the link was confirmed by Lewis's lectures. I have, however, never been able to locate her source. Apparently, Jadis's presence was supposed to slip "in and out of Lewis's books" in "other forms." Lilith herself is said to be, "a fierce spirit of myriad names and many shapes."
Aside from her personality and perilous beauty, Lilith is most evident in Jadis's use of the Deplorable World. In the Garden of Eden, Lilith was said to invoke the mysterious name of God in order to grow wings and fly from Paradise. Her ancestress Isis also knew the hidden name of the Sun God and used it to make herself the head of the Egyptian pantheon. Fiction or not, Jadis belongs to a powerful legacy. If Lewis's Narnia books were part of the public domain, along with the Brothers Grimm and the "modern" fairytales of Lewis Carrol and L.Frank Baum (creators of Wonderland and Oz, respectively), Jadis would probably have her own novel by now.