Billina

In Ozma of Oz (1907) Dorothy and her party are caught in a storm at sea; Dorothy is washed ashore into the uncharted country of Ev inside a chicken coop and finds Billina, who was originally named 'Bill' because no one could tell whether she was a hen or a rooster. Dorothy insists on the feminine form and Billina accompanies Dorothy to Oz, eventually settling in the Emerald City.

Baum's prose describes Billina as a hen, repeatedly called a 'yellow hen' in the Ozma of Oz text. Adaptations vary in depiction—she is represented by an animatronic/puppet in the 1985/1986 Return to Oz film and is depicted as red in at least one animated series—while Baum's original text emphasizes a domesticated hen's appearance.

Billina speaks in a sharp, talkative voice and displays a spunky, sassy temperament; she functions as Dorothy's animal companion and conversational interlocutor. Within the fictional rules of Ozma of Oz, eggs are dangerous to the Nome King and his kind, and Billina's laying of an egg contributes directly to the Nome King's defeat. Beyond speech, social agency, and ordinary hen behavior (laying eggs, hatching chicks), Baum's texts do not ascribe supernatural powers to her.