Elizabeth is a member of the Wizard's Council. She is one of the girls from Glinda's boarding school / orphanage.
One of the requirements for the women in the Council is that they remain chaste, focused only on the matters of the mind, not that of the flesh.
Elizabeth is revealed to be a spy for Glinda, planted in the Council to derail Wizard's plans and report to the Witch of the North.
She helps Lucas/Roan and Silvie escape the Wizard and is put to death, together with the rest of the Council, by being thrown into a pit with a young fire witch.