Who created the series who has Peter Brown as the protagonist ?
Peter Brown (Oz):  Thompson used Peter as the protagonist in three of her books: "The Gnome King of Oz" (1927), "Jack Pumpkinhead of Oz" (1929), and "Pirates in Oz" (1931). Pirates in Oz: Pirates in Oz (1931) is the twenty-fifth in the series of Oz books created by L. Frank Baum and his successors, and the eleventh written by Ruth Plumly Thompson.
L. Frank Baum