Cap'n Bill is a fictional character found in L. Frank Baum's Land of Oz. Cap'n Bill was introduced in Baum's fantasy novels The Sea Fairies (1911) and Sky Island (1912) and first appeared in Oz in The Scarecrow of Oz (1915), the ninth book in the Oz series.
Cap'n Bill is an ex-sailor with a wooden left leg from the knee down. His head is almost bald and what little hair he has is grizzled. His eyes are pale blue with a gentle look to them, and his face is round, rugged, and bronzed. He has been Trot's companion from birth as he was her mother's star boarder. Formerly he was captain of a schooner, and Trot's father was his mate; after losing his leg the Cap'n retired, and Trot's father was promoted to captain of the same ship. Cap'n Bill and Trot also play significant roles in the later Oz books, The Lost Princess of Oz (1917), The Magic of Oz (1919) and The Magical Mimics in Oz (1946).