Ozroar is not a creation of the Royal Historians of the "Famous Forty" Oz books; rather, he is found in later Oz literature and fan fiction. He is sometimes though not always called the first king of Oz, though this contradicts the details in L. Frank Baum's original works — in Dorothy and the Wizard in Oz Baum suggests a long line of earlier monarchs.
Ozroar first appears in Henry Blossom's The Blue Emperor of Oz. He recurs in later works, including The Forest Monster of Oz by Chris Dulabone and Robert Evans, and Prince Pompadore in Oz by Nathan DeHoff. (Author Blossom made Ozroar the brother of King Pompus of Pumperdink as well as Ozma's grandfather.)