This is a list of characters in the original Oz books by American author L. Frank Baum. The majority of characters listed here unless noted otherwise have appeared in multiple books under various plotlines. Oz is made up of four divisions that surround the Emerald City in the center. The country as a whole was originally enchanted by a character named Queen Lurline, who is described in the Oz backstory. Additional characters were added in regions surrounding the Land of Oz (beyond the deserts) as the series progressed.

Aunt Em and Uncle Henry appear in The Wonderful Wizard of Oz (1900). They are Dorothy Gale's guardian aunt and uncle. They live a joyless and gray life on a small farm on the prairies of Kansas. Neither of them believe their niece when she tells them she has been to the Land of Oz; they consider her a mere dreamer, as her dead mother had been. This changes when the two later face foreclosure on their farm. Dorothy arranges with Princess Ozma to bring them to Oz, so that they can escape their bleak fates and be safe and finally content. Eventually, in The Emerald City of Oz (1910), they move permanently to Oz and take up jobs there.

Betsy Bobbin is a fictional character in L. Frank Baum's Land of Oz. Betsy is portrayed with various hair colors throughout the series; in her initial appearances her hair was colored as blonde, strawberry blonde or light brown. Later appearances depicted her as brunette or with auburn hair. Betsy first appears in Baum's 1913 stage play The Tik-Tok Man of Oz, and then in his 1914 novel Tik-Tok of Oz (partly a novelization of the play), wherein she teams up with the Shaggy Man and together they go to the Nome King's Caverns.

In the book series, Betsy arrives to Oz from Oklahoma with a mule named Hank, and she is shown as a constant companion of both Dorothy and Trot in the later books. In The Lost Princess of Oz (1917), she is said to be one year older than Dorothy Gale. Betsy is more passive than Dorothy, and in one book she is described as shy. Betsy was later made a Princess of Oz by Ruth Plumly Thompson, and she also appears as the protagonist of Thompson's The Hungry Tiger of Oz (1926) in which she helps a young prince from an Evian kingdom called Rash regain his throne from a wicked uncle.

Billina is Dorothy's pet hen on the Kansas farm and first appears in the book Ozma of Oz (1907), in which she saves the citizens of Oz from being turned into decor objects by the evil Nome King. She is sassy and talkative; at the conclusion of Ozma of Oz, Billina chooses to stay in Oz and live in the Emerald City's royal palace, later becoming the matriarch of a large colony of chicks. She is a major character in Walt Disney's 1985 live-action film Return to Oz, in which she helps Dorothy save the Land of Oz from near extinction.

Boq is a minor character who appears in the beginning of The Wonderful Wizard of Oz (1900). He is depicted as a wealthy Munchkin man with a large family who offers Dorothy Gale and Toto shelter after throwing a lavish banquet in Dorothy's honor upon her arrival to the Land of Oz.

A reimagined version of the character appears in Gregory Maguire's 1995 revisionist parallel novel Wicked, where he is a childhood friend and schoolmate of Elphaba (Maguire's reimagining of the Wicked Witch of the West). Boq is reimagined further in the novel's Broadway musical adaptation, where he is made a composite character with the Tin Woodman. In the musical's two-part film adaptation (2024–2025), he is portrayed by Ethan Slater and his character arc is expanded upon, complete with him being given the surname Woodsman.

The Braided Man is a bent-over old man with his hair and beard in braids who lives halfway up Pyramid Mountain. He is a great inventor who used to live on the surface of the Earth where he worked with holes until a big one caused him to fall deep underground where he landed on Pyramid Mountain and lived on its spiral staircase since. Since then, he has amused himself by making Flutters and Rustlers.