# Dark horse
A dark horse is a person who was previously little known and then emerges to prominence in a competition, such as a race, an election, or a contest for a position.[1](https://www.phrases.org.uk/meanings/dark-horse.html)
| Key fact | Detail |
|---|---|
| Meaning | Someone previously little known who emerges to prominence in a competition[1](https://www.phrases.org.uk/meanings/dark-horse.html) |
| Origin | Horse racing slang for a horse of unknown form, difficult to place odds on[1](https://www.phrases.org.uk/meanings/dark-horse.html) |
| Earliest known use | Benjamin Disraeli, *The Young Duke*, 1831[1](https://www.phrases.org.uk/meanings/dark-horse.html) |
| First political use | James Polk, the surprise nominee at the 1844 Democratic Convention, who went on to become president[2](https://www.gcetece.org/_files/ugd/374af4_030f217df3aa4c6593efd8a7d7f8c499.pdf) |
| Widespread use | The term was in wide use by 1865[2](https://www.gcetece.org/_files/ugd/374af4_030f217df3aa4c6593efd8a7d7f8c499.pdf) |
| Racing relative | An outsider, or longshot, is a runner with little chance of winning on paper, offered at relatively long odds[3](https://racingguide.co.uk/what-is-meant-by-the-terms-odds-on-and-outsider/) |
## Origin in horse racing
The phrase comes from nineteenth-century British horse racing. A dark horse was one about which little was known, so bookmakers and bettors found it difficult to place odds on it.[1](https://www.phrases.org.uk/meanings/dark-horse.html) Brewer's *Dictionary of Phrase and Fable* records the same racing sense: a horse of good pretensions, but of which nothing is positively known by the general public.[4](https://homepage.villanova.edu/michael.foight/brewersdictphrasefable.pdf) The "dark" in the phrase refers to the obscurity of the horse's record, not to the color of its coat.[5](https://didyeah.com/facts/a-dark-horse-was-an-unknown-race-entrant-not-a-horse-with-dark-hair)
**Earliest known reference.** [Benjamin Disraeli](https://www.edgepedia.org/benjamin-disraeli), the British novelist and later Prime Minister, provides the earliest known reference to the phrase in his 1831 novel *The Young Duke*, which describes a race in which "a dark horse, which had never been thought of … rushed past the grand stand in sweeping triumph."[1](https://www.phrases.org.uk/meanings/dark-horse.html) A fuller version of the passage adds that the careless St James "had never even observed on the list" the horse that won.[6](https://www.diacronia.ro/indexing/details/A2754/pdf) One reference work dates the novel to 1835 rather than 1831, but the majority of the sources give 1831.[7](https://literarydevices.net/dark-horse/)
## Spread into figurative use
The figurative use seems first to have been taken up for candidates for academic preferment. *The Saturday Review* wrote in 1860 that a headship was "often given by the College conclaves to a man who has judiciously kept himself dark," and *Sketches from Cambridge* observed in 1865 that "every now and then a dark horse is heard of, who is supposed to have done wonders at some obscure small college."[1](https://www.phrases.org.uk/meanings/dark-horse.html) By 1865 the term was in wide use.[2](https://www.gcetece.org/_files/ugd/374af4_030f217df3aa4c6593efd8a7d7f8c499.pdf)
## Politics: the dark horse candidate
In politics, a dark horse candidate is one whose nomination or victory is unexpected.[8](https://www.annenbergclassroom.org/glossary_term/dark-horse/) James Polk, the first dark horse in American politics, emerged from the Democrats' 1844 convention and was later elected president.[2](https://www.gcetece.org/_files/ugd/374af4_030f217df3aa4c6593efd8a7d7f8c499.pdf) Despite the unexpectedness of his nomination, Polk went on to prove himself as one of the most impactful single-term presidents the United States has had, presiding over Texas joining the Union and over the United States gaining California, Oregon, and the whole of the American South-West.[9](https://www.lexistry.com/phrase/dark-horse)
The term remains current in political commentary, where a dark horse candidate can take a role or a nomination by surprise when the leading contenders no longer fit the requirements.[10](https://dictionary.cambridge.org/us/dictionary/english/dark-horse?topic=horse-racing)
## The dark horse in racing and betting markets
The racing term sits alongside related vocabulary. An outsider, also called a longshot, is a runner that has, at least on paper, little chance of winning a race and is consequently offered at relatively long odds compared with some or all of its rivals.[3](https://racingguide.co.uk/what-is-meant-by-the-terms-odds-on-and-outsider/) A horse racing longshot is typically defined as any horse with odds of 15/1 or longer, though the threshold varies by market and context.[11](https://betmana.co.uk/glossary/longshot/)
Market position does not determine the result. Odds that labeled a horse an outsider beforehand can prove conservative, and the horse can beat higher-priced expectations.[12](https://racecards.co.uk/guides/questions/odds-outsider) Betting-market research describes a favorite-longshot bias, a tendency for long-priced selections to produce poorer returns relative to their apparent probabilities than shorter-priced selections, because longshots tend to be overbet relative to their true chances.[13](https://www.britishracecourses.org/horse-racing-favourite-longshot-bias-explained/) This bias concerns the price rather than the possibility of winning: a horse with a genuine 1 percent winning chance will occasionally win, but that does not make it a good bet at 50/1.[13](https://www.britishracecourses.org/horse-racing-favourite-longshot-bias-explained/)
## Modern usage
Today a dark horse can be any unexpected contender, from a political candidate to a tournament team.[5](https://didyeah.com/facts/a-dark-horse-was-an-unknown-race-entrant-not-a-horse-with-dark-hair) The expression conveys a subtle sense of respect: calling someone a dark horse means they are more than just an unknown quantity, since their abilities were there the whole time, hidden from view.[9](https://www.lexistry.com/phrase/dark-horse) A dark horse may also surprise observers without winning; the essential feature is that its strength was not well known beforehand.[5](https://didyeah.com/facts/a-dark-horse-was-an-unknown-race-entrant-not-a-horse-with-dark-hair) The Cambridge dictionary also records a British informal use for a person with hidden abilities, as in "Anna's such a dark horse, I had no idea she published a novel."[10](https://dictionary.cambridge.org/us/dictionary/english/dark-horse?topic=horse-racing)
## References
1. [A Dark Horse, Meaning & Origin of the Phrase, Phrase Finder](https://www.phrases.org.uk/meanings/dark-horse.html)
2. [Gambling and Good Government Program Materials, Albany Law School](https://www.gcetece.org/_files/ugd/374af4_030f217df3aa4c6593efd8a7d7f8c499.pdf)
3. [What is meant by the terms 'odds-on' and 'outsider'?, Horse Racing Guide](https://racingguide.co.uk/what-is-meant-by-the-terms-odds-on-and-outsider/)
4. [Dictionary of Phrase and Fable (Brewer)](https://homepage.villanova.edu/michael.foight/brewersdictphrasefable.pdf)
5. [The Racehorse Origin of 'Dark Horse', DidYeah](https://didyeah.com/facts/a-dark-horse-was-an-unknown-race-entrant-not-a-horse-with-dark-hair)
6. [Horses for Courses, Diacronia](https://www.diacronia.ro/indexing/details/A2754/pdf)
7. [Dark Horse, Meaning, Origin, Examples, Literary Devices](https://literarydevices.net/dark-horse/)
8. [Dark Horse, Annenberg Classroom](https://www.annenbergclassroom.org/glossary_term/dark-horse/)
9. [Dark Horse, Meaning & Origin, Lexistry](https://www.lexistry.com/phrase/dark-horse)
10. [DARK HORSE, Cambridge English Dictionary](https://dictionary.cambridge.org/us/dictionary/english/dark-horse?topic=horse-racing)
11. [Longshot, Betting Glossary, Betmana](https://betmana.co.uk/glossary/longshot/)
12. [Does outsider mean a horse cannot win?, RaceCards.co.uk](https://racecards.co.uk/guides/questions/odds-outsider)
13. [Horse Racing Favourite-Longshot Bias Explained, British Racecourses](https://www.britishracecourses.org/horse-racing-favourite-longshot-bias-explained/)
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*Topic: Encyclopedia › Sports, games, and recreation › Individual sports and outdoor recreation › Equestrian and animal sports › Horse racing › Horse racing culture, media, and regulation › Horse racing betting and handicapping*
*Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026; Oct 21, 2026 · Edited: Sep 30, 2026; Oct 21, 2026 · Last review: Oct 21, 2026*
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