The Broken Ear (French: L'Oreille cassée, originally published in English as Tintin and the Broken Ear) is the sixth volume of The Adventures of Tintin, the comics series by the Belgian cartoonist Hergé. Commissioned by the conservative Belgian newspaper Le Vingtième Siècle for its children's supplement Le Petit Vingtième, it was serialised weekly from December 1935 to February 1937. The story tells of young Belgian reporter Tintin and his dog Snowy, as he searches for a stolen South American fetish, identifiable by its broken right ear, and deals with other thieves who are after it. In doing so, he ends up in the fictional nation of San Theodoros, where he becomes embroiled in a war and discovers the Arumbaya tribe deep in the forest.

The Broken Ear was a commercial success and was published in book form shortly after its conclusion. Hergé continued The Adventures of Tintin with The Black Island, while the series itself became a defining part of the Franco-Belgian comics tradition. In 1943, The Broken Ear was coloured and reformatted for republication by Casterman. Commentators have praised the book for showcasing Hergé's then-newfound commitment to a clear narrative structure and strives for historical and technical accuracy. The Broken Ear introduces the recurring character General Alcazar, and was the first to include fictional countries. The story was adapted for both the 1956 Belvision animation, Hergé's Adventures of Tintin, and for the 1991 Ellipse/Nelvana animated series The Adventures of Tintin.

A fetish created by the Arumbaya tribe of South America is stolen from Brussels' Museum of Ethnography, only to be returned the following day. Tintin realizes that the replacement is a fake, and draws a connection with a local sculptor, Jacob Balthazar, who has just been murdered. Balthazar's parrot – the only witness to the murder – is obtained by two Hispanic men, Alonso and Ramón, who try to kill Tintin when he begins to investigate their connection to the crime. From the parrot, Alonso and Ramón discover Balthazar's murderer is Rodrigo Tortilla, and they proceed to follow him aboard a ship bound for South America. There, they murder Tortilla, but find that he did not have the original fetish. Tintin, however, follows them, and arranges their arrest when the ship docks at Los Dopicos, capital of San Theodoros. Nevertheless, the corrupt colonel in charge of the arrest allows the antagonists to slip away, and detains Tintin.

In the city, Tintin is framed as a terrorist, arrested, and sentenced to death by firing squad. Tintin survives when a revolution topples the government, and the new leader, General Alcazar, appoints Tintin to be his aide-de-camp. Alonso and Ramón capture Tintin, and interrogate him in the hope of locating the missing fetish, but they only end up briefly put behind bars by him. As aide-de-camp, Tintin opposes the proposed decision of San Theodoros claiming the supposedly oil rich Gran Chapo, as this would cause a war between San Theodoros and neighboring Nuevo Rico, and he is framed as a traitor by warmongering oil and weapon companies. Nevertheless, Tintin's new friend Pablo frees him from imprisonment, allowing for Tintin to flee to Nuevo Rico. However, in the process, he inadvertently causes events that have Nuevo Rico start a war between it and San Theodoros.

Once within Nuevo Rico, Tintin decides to enter the forest and find the Arumbaya tribe, hoping they can explain to him why people wish to steal the fetish. Finding a British explorer, Ridgewell, living among the Arumbaya, Tintin learns that a diamond was hidden inside the statue. At the check-in counter, Tintin and Snowy were due to leave South America for Europe but missed the ferry crossing as they had to wait for another week. As the war between San Theodoros and Nuevo Rico ends when Gran Chapo is discovered to have no oil, Tintin returns to Belgium after a brief encounter with Alonso and Ramón. There, Tintin discovers Balthazar's brother has been producing a range of exact replicas of the fetish, which he had discovered among his deceased brother's belongings. Tintin learns it was purchased from him by Samuel Goldbarr, a wealthy American now returning to the United States with it by ship. Catching up to the boat, Tintin finds Alonso and Ramón aboard. His struggle with them for the possession of the fetish results in it smashing on the floor, and the diamond hidden in it rolling overboard into the sea. Alonso and Ramón try to kill Tintin for making them lose it, and the three of them accidentally fall overboard as well. Tintin is rescued, but Alonso and Ramón drown. Goldbarr allows Tintin to return the stolen fetish to the museum, where it is repaired and put back on display, albeit comically damaged.

Georges Remi—best known under the pen name Hergé—was employed as editor and illustrator of Le Petit Vingtième ("The Little Twentieth"), a children's supplement to Le Vingtième Siècle ("The Twentieth Century"), a staunchly Roman Catholic, conservative Belgian newspaper based in Hergé's native Brussels which was run by the Abbé Norbert Wallez. In 1929, Hergé began The Adventures of Tintin comic strip for Le Petit Vingtième, revolving around the exploits of fictional Belgian reporter Tintin. Wallez ordered Hergé to set his first adventure in the Soviet Union as anti-socialist propaganda for children (Tintin in the Land of the Soviets), to set his second adventure in the Belgian Congo to encourage colonial sentiment (Tintin in the Congo), and to set his third adventure in the United States to use the story as a denunciation of American capitalism (Tintin in America). Wallez was subsequently removed from the paper's editorship following a scandal, although Hergé was convinced to stay on the condition of a salary increase. In preparing The Broken Ear, Hergé developed the new habit of keeping plot notes and ideas in a notebook. He also began making cuttings of photographs and other images from magazines and newspapers, filing them away for future use; he used them as a basis for many of the drawings in The Broken Ear.

Hergé used The Broken Ear to allude to real events that had recently taken place in South America. The fictional countries of San Theodoros and Nuevo Rico were based on the real countries Bolivia and Paraguay, while the Gran Chapo War depicted in the strip was an allusion to the Chaco War (1932–35) that was waged between Bolivian and Paraguayan forces over lucrative oil fields in the Gran Chaco region. The name "Gran Chapo" was a pun on the French grand chapeau, meaning "big hat", while the name Nuevo Rico was a pun on nouveau riche and the name of the Nuevo Rican capital city, Sanfación, was a pun on sans façon, meaning "without manners". Hergé's character Basil Bazarov, of the Vicking Arms Company Ltd (Basil Mazaroff in the 1937 edition), was a thinly veiled allusion to the real-life Greek weapons seller Basil Zaharoff of Vickers Armstrong, who profited from the conflict by supplying arms to both Paraguay and Bolivia. Hergé had learned about the conflict and the western corporations profiting from it through two issues of anti-conformist French magazine Le Crapouillot (The Mortar Shell), which covered news stories ignored by the mainstream media. It is also likely that he had read Richard Lewinsohn's 1930 book Zaharoff, l'Européen mystérieux (Zaharoff, the Mysterious European), which had been referenced in Le Crapouillot.

Hergé's Arumbaya fetish was based on the design of a genuine Peruvian statue in Brussels' Royal Museums of Art and History; a pre-Columbian Chimu statue, it was made of wood and dated to between 1200 and 1438 CE. Whereas Hergé had access to speakers of Mandarin when creating The Blue Lotus, he had no access to speakers of indigenous Amerindian languages, and as such, the Arumbaya language that he developed was entirely fictitious. He based its structure largely on the Brusseleir dialect spoken in the Marolles area of Brussels, mixed with Spanish endings and constructions. In developing the Arumbaya's rivals, the Bibaros, he was influenced by anthropological accounts of head shrinking among the Jibaros tribes; when Leslie Lonsdale-Cooper and Michael Turner translated the book into English, they renamed the Bibaros as the Rumbabas, a pun on the rum baba pudding. The explorer Ridgewell, found living among the Arumbayas is based upon the British explorer Colonel Percy Harrison Fawcett, who mysteriously disappeared into the Amazon jungle in 1925. In crafting the story, Hergé was possibly influenced by The Maltese Falcon, as there are similarities in their plots.