The Island of California refers to a long-held global misconception, dating from the 16th century, that the California region was not part of mainland North America but rather a large island separated from the continent by a strait now known as the Gulf of California.

Las Sergas de Esplandián is a novel written by Garci Rodríguez de Montalvo in the late fifteenth or early sixteenth century. The novel is a sequel to a popular fifteenth century set of chivalric romance novels, Amadís de Gaula. The novel achieved particular notability in 1862, when Edward Everett Hale concluded that the novel was the origin of the name California.