Tarzan and the Madman is a novel by American writer Edgar Rice Burroughs, the twenty-third in his series of twenty-four books about the title character Tarzan. Written from January to February 1940, the story was never published in Burroughs' lifetime.^[2][3] The book was first published in hardcover by Canaveral Press in June 1964, and in paperback by Ballantine Books in February 1965.^[3][4][5]

Tarzan tracks down a man who has been mistaken for him. The man is under the delusion that he is Tarzan, and he is living in a lost city inhabited by people descended from early Portuguese explorers. The plot devices of a lost city and a Tarzan "double" or impostor had been used by Burroughs in some previous Tarzan novels.