"I'm Not that Girl" is a song from the musical "Wicked", sung by Elphaba Thropp, who plays which future character?
I'm Not that Girl:  It is a solo sung by the main character of the show, Elphaba Thropp (the future Wicked Witch of the West in "The Wonderful Wizard of Oz") in the first act and Glinda in the reprise in the second act. Wicked Witch of the West: The Wicked Witch of the West is a fictional character created by L. Frank Baum as the most significant antagonist in his classic children's novel "The Wonderful Wizard of Oz" (1900).
Wicked Witch of the West