A champion is someone who has repeatedly come out first among contestants in a challenge or other test, one who is outstandingly skilled in his field. A knightly companion of the king within the court is also called a paladin (from the "palace" Latin palatium). In contrast, the champion defends his lord's honor upon the field (French champs) of battle or in the lists at a tournament, the "field of honor.". In the Arthurian cycle of tales, Launcelot was the champion who defended Guinevere's innocence. In medieval society, where courtiers were fighters and mounted fighters were invariably noblemen, the terms paladin and champion drew together.

A champion may take up a more abstact cause, as Ralph Nader made himself a champion for car-buyers, a consumer's advocate. In an ideological sense, encompassing religion, a champion may be an evangelist, a visionary advocate who clears the field for the triumph of the idea. Or the champion may merely make a strong case for a new corporate division to a resistant board of directors. Such a champion may take on responsibility for publicizing the project and garnering funding. Such a champion is beyond a simple promoter.

The champion of a neophyte is more often thought of as a mentor.

In sports, a champion is the athlete or team in first place at the end of a season of competition (and, if applicable, any associated playoffs). The championship is typically commemorated with sports memorabilia (for the team's fans) and a trophy. Many sports commemorate championship titles with rings; in the United States the championship rings for all "major league" sports are manufactured by Jostens, Inc.

Champion is a title awarded by the American Kennel Club in recognition of a dog that closely matches its breed standard. The title is earned by competition in the show ring. Blue ribbon purebred dogs that have won such first-prize at A.K.C. dog shows are certified "Champions" and receive the honorific prefix "Ch." before their name, the canine equivalent of "Hon.".

Several movies have been titled Champion. The road to becoming more than just a winning fighter, a true champion, is the running theme of the Rocky movies of Sylvester Stallone. Champion the Wonder Horse was a children's TV series broadcast in the 1950s.

Naturally "Champion" has been adopted as a brand-name across the board, most famously for a brand of spark plugs.