Elphaba is the most popular of the Wicked Characters, and for good reason. She is the center of the storyline and plot, both in the play and in the original novel. The character made the list of the 100 Greatest Characters in the last 20 years (by Entertainment Weekly), and is a rich and complex character.
Her green skin makes her an outcast and gives her a sense of burden, intensity, perhaps frames as a “chip on her shoulder” for the causes of the downtrodden. She faces heartbreak, perceived inadequacy, and family issues. The character contrasts and subverts the original Wizard of Oz story by presenting conflict with the eventual “Good Witch” Glinda Upland.
In the play we first see her as a Baby, then eventually as a teenager as she goes off to Shiz University. We see her progression from a outcast young woman to a strong, confident person fighting for the cause of others.
Fun Fact: Novelist Gregory Macquire came up with the name Elphaba by using the initials of L. Frank Baum, the original author of the Wizard of Oz. L, F, and B became Elphaba. Contrast this with the legend that Baum himself came up with the term “Oz” by looking at an encyclopedia on his bookshelf. The encyclopedia covered the letters O through Z, i.e. OZ.