Frederick E. Otto (1925 – 1994) was an Oz scholar and author. He is best known for his Index to the Baum Bugle, first published in 1986 and with subsequent editions in 1988 and 2002.
Otto also wrote the books The Lost Emeralds of Oz and The Oziads (both published posthumously in 1995). His stories have appeared in Oziana. The Oziads retells Oz stories in verse form. In The Lost Emeralds of Oz, Otto offers his own explanation for the fact the visitors to the Emerald City must wear green-tinted eyeglasses in The Wonderful Wizard of Oz.
The International Wizard of Oz Club named its prize for new Oz fiction the Frederick E. Otto Award.
The Frederick E. Otto Memorial Scholarship Fund is located in San Francisco.