A dark horse candidate is one who is nominated unexpectedly, without previously having been discussed or considered as a likely choice. Often a dark horse is selected as a compromise when other, more prominent candidates' factions cannot come to an agreement.

Famous dark horse candidates for the US Presidency include James Knox Polk, elected in 1844 after unexpectedly winning the Democratic nomination instead of Martin Van Buren or Henry Clay, and John W. Davis, the unsuccessful Democratic nominee in 1924 who was chosen in a compromise instead of Al Smith or William G. McAdoo.

Dark Horse Comics is a comic book publisher.

Dark Horse is also the title of a famous song by George Harrison.