Tik-Tok of Oz is the eighth book in the Oz series written by L. Frank Baum, published on June 19, 1914. The book has little to do with Tik-Tok and is primarily the quest of the Shaggy Man (introduced in The Road to Oz) to rescue his brother, and his resulting conflict with the Nome King. The book was based on Baum's play The Tik-Tok Man of Oz, which was produced in Los Angeles in spring 1913. It was followed by The Scarecrow of Oz (1915).

The endpapers of the first edition held maps: one of Oz itself, and one of the continents on which Oz and its neighboring countries belonged. These were the first maps printed of Oz.

Queen Ann Soforth of Oogaboo, a small monarchy separated from the rest of Oz's Winkie Country, sets out to raise an army to conquer Oz.

Betsy Bobbin, a girl who is a year older than Dorothy Gale, and her loyal mule Hank have washed ashore during a storm. They arrive at a large greenhouse that is the domain of the Rose Kingdom, where the roses tell them that no strangers are allowed. Just as the Royal Gardener is about to pass sentence on Betsy and Hank, the Shaggy Man falls through the greenhouse's roof, and charms the Gardener into sparing all of their lives with his Love Magnet. The travelers leave, taking with them the newly plucked Rose Princess Ozga, a cousin of Ozma, the ruler of Oz.

The Shaggy Man relates how Ozma sent him here via the Magic Belt because he wanted to find his brother, who went digging underground in Colorado and disappeared. He surmised that the Nome King, ruler of the underground Nome Kingdom, captured him. They meet up with Polychrome the Rainbow's Daughter, and they rescue Tik-Tok from the well where the Nome King had tossed him. Once Tik-Tok is wound up, he accompanies Betsy, Hank, the Shaggy Man, Ozga, and Polychrome to their chance encounter with Queen Ann and her army. When Queen Ann learns of the riches to be found in the Nome King's underground kingdom, she calms down and accepts the services of Tik-Tok as her new private.

The Nome King is aghast at this group coming toward his underground kingdom. Since no one can be killed in Oz, the Nome King seeks to discourage them, first by taking them through the Rubber Country, and then disposing of them by dropping them through the Hollow Tube, a conduit leading to the other side of the world. There the party enters the jurisdiction of the immortal called Tititi-Hoochoo, the Great Jinjin, who vows to punish the Nome King for using the Hollow Tube. He sends Tik-Tok and the others back with his Instrument of Vengeance, a lackadaisical dragon named Quox.

When Quox bursts through the Nome King's cavern, the Nome King sees the ribbon around Quox's neck and forgets all the magic he ever knew. The Nome King is driven out of his kingdom when Quox releases six eggs from the padlock around his neck. The eggs, poisonous to Nomes, follow the Nome King to the Earth's surface and confine him there.

The new Nome King, the former chief steward Kaliko, vows to help the Shaggy Man find his brother, whom he knows is in the Metal Forest. The Shaggy Man meets his brother in the center of the Forest, but the brother is cursed with a charm of ugliness by the former Nome King. The fairy Polychrome's kiss restores the Shaggy Man's brother to his former self.