Rahne Sinclair is a Marvel Comics character. Her debut was in the 1982 graphic novel, New Mutants. She has been on more X-teams than any other character, including Cyclops and Wolverine. She was created by Chris Claremont and Bob McLeod.
Rahne's history and profile are given in great detail at:
Below is the text that accompanied Bill Sienkiewicz's pinup of Rahne in the back of New Mutants #22, way back in 1984.
Comments from Prof. Xavier's Journal:
Rahne Sinclair - Wolfsbane. A specific metamorph able to transform from human to wolf... with a transitional incarnation roughly halfway between the two.
She was the first New Mutant. Indeed, it was in great measure because of her that I decided to gather this class of novice students.
By far the youngest... in temperment, if not in actual age. She is an orphan, whose unusually strict and conservative upbringing has left her painfully shy and insecure. It hasn't been easy for her to adjust, not only to the manifestation of her mutant abilities, but as well to the environment in which she now lives.
She has so much potential, both as a mutant and a person... I must find a way to help her realize it. More and more these days, however, she takes refuge in her lupine form. The world is much simpler to her then. There are no ambiguities or confusion. She is starting to like that life more than being human.