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The term began as horse racing parlance for a race horse that is not known to gamblers and thus is difficult to place betting odds on.
The earliest-known mention of the concept is in Benjamin Disraeli's novel The Young Duke (1831). Disraeli's protagonist, the Duke of St. James, attends a horse race with a surprise finish: "A dark horse which had never been thought of, and which the careless St. James had never even observed in the list, rushed past the grandstand in sweeping triumph."
In the political arena 
Politically, the concept came to America in the nineteenth century when it was first applied to James K. Polk, a relatively unknown Tennessee Democrat who won the Democratic Party's 1844 presidential nomination over a host of better-known candidates. Polk won the nomination on the ninth ballot, and went on to win the presidential election.
- Franklin Pierce, chosen as the Democratic nominee and later elected the 14th president in 1852.
- Abraham Lincoln, chosen as the Republican nominee and elected as the 16th president in 1860.
- Rutherford B. Hayes, elected the 19th president in 1876.
- James A. Garfield, elected the 20th president in 1880.
- Warren G. Harding, elected the 29th president in 1920 after his surprise nomination.
- Jimmy Carter, elected the 39th president in 1976; in the beginning of that same year, Carter was a relative unknown outside his home state of Georgia.,
Outside of the United States, the dark horse status also attributed to Alberto Fujimori, who rose to the Presidency in Peru and Jejomar Binay, who rose to the Vice Presidency in the Philippines.
In a 2011 article about possible successors for Hugo Chávez, Sarah Grainger for the BBC News website referred to former army officer Diosdado Cabello, who helped Hugo Chávez to stage a failed coup in 1992, as a dark horse.
Several government ministers, who were appointed to the third cabinet of Russian prime minister Dimitri Medvedev on 21 May 2012, were also described as "dark horses" due to lacking experience, for instance, Olga Golodets, Vladimir Medinsky and Alexander Novak. Some of the candidates for the presidency of Iran in 2013 were labelled as dark horse, including Mohammad Baqer Qalibaf, Mohsen Rezai, Mostafa Pourmohammadi and Mohammad Saeedikia.
Use in music, film and television 
In addition, surprising or unlikely nominations for such prizes as the Academy Award (awarded by the Academy of Motion Picture Arts and Sciences) are referred to as dark horses.
Guitarist and singer-songwriter George Harrison was nicknamed the "dark horse" of The Beatles, as his visibility as a songwriter and vocalist increased later in the Beatles' career, particularly on Abbey Road. Harrison went on to name his solo label Dark Horse Records, and to release both an album and a song named "Dark Horse."
American Idol season 8 winner Kris Allen was coined as the "dark horse" of the competition as he went on to win the competition and defeat the crowd favorite and front-runner Adam Lambert.
The first episode of the second season of Frisky Dingo is called "Behold A Dark Horse."
Carol Peletier from AMC's The Walking Dead can be considered a dark horse of the series due to her outliving comic book characters who had much larger roles such as Dale and Andrea. With the conclusion of season 3 she is the only original female character still alive.
Use in publishing 
Dark Horse Comics is an American comic book publisher.
See also 
- "A dark horse". The Phrase Finder.
- "Dark horse". Merriam Webster.
- "Origins of Sayings - A Dark Horse". Trivia Library.
- "Who Will Be Iran's Next President?". Radio Free Liberty. 6 January 2013. Retrieved 19 April 2013.
- "Invest in Philippines, the 'Dark Horse' of Asia". CNBC. 17 November 2011.
- Tikhomirov, Vladimir (22 May 2012). "Putin names a technocrat Cabinet". Equity. Retrieved 28 March 2013.
- Grainger, Sarah (28 July 2011). "Who could succeed Hugo Chavez as Venezuela's leader?". BBC News.