Literal Meaning (referring to a horse):
* The grey mare, a dark horse in the race, surged ahead in the final stretch and took the lead.
Figurative Meaning (referring to a person or thing):
* Dark horse candidate Emily Jones won the election, surprising everyone with her impressive campaign.
* The company's new product, a dark horse in the market, quickly gained popularity and outsold its competitors.
* In the debate, the dark horse student surprised everyone with her insightful arguments and well-researched points.
Informal Usage:
* "Don't underestimate that team," said the coach. "They're a dark horse and could pull off an upset."
* "I'm not sure who's going to win the contest," said the judge. "It's anyone's game – there are a lot of dark horses in the competition."
Note: "Dark horse" is often used to describe someone or something unexpected, and usually successful.