Oporos, the "polter-Monkey" was a small, spirit Monkey with blue-gold fur who appeared to Elphaba during her childhood in Quadling Country.
He claimed to Elphaba to be hiding near the Thropp missionary camp after their own clan was scattered by jaguars. He appears only to Elphaba when she was a child. She also sees a vision of him escorting the spirit of Melena after own death. He appears briefly in Elphie: A Wicked Childhood.