An also-ran is a term to describe someone who lost a race, either athletic or political, by a large margin, or someone of little significance. It is always hyphenated. The plural is also-rans
Its synonyms include nonstarter and loser. The thesaurus we referenced listed dark horse as a similar term, however, a dark horse or sleeper is an unsuspected victor, not failure.
As you can see by the ngram below, also-ran has had a dramatic increase in popularity since its coinage at the turn of the twentieth century. It was first used to describe horses who also ran in a race and did not place.
Examples
Texas Gov. Rick Perry got some good news last week. In a FOX News poll, Perry moved from an also-ran in the contest for the 2016 Republican presidential nomination to a tie for first place with former Florida Gov. Jeb Bush. [WUWM].
“I know I’m in the right spot, and I don’t feel like I’m just going to be an also-ran now,” Levins said. “I feel like I’m a deserving member of my team.” [Chronicle Herald]
Volvo Cars Australia boss Matt Braid watched as McLaughlin went from front-row favourite to anonymous also-ran in both races. [Sydney Morning Herald]
This time, the Cowboys and Giants don’t look like also-rans, but factors even for the conference championship. [Sporting News]
The spectators get the chance to cheer their favourites and enjoy the sadistic pleasure of seeing the also-rans humiliated while thanking their stars that it’s not them in the arena. [Express]