A one-shot is a comic book that is a pilot or a stand-alone story created as a single issue, rather than the more typical series format.
In the United States, one-shots are usually labeled with a "#1" despite there being no following issues, and are sometimes subtitled as "specials". On occasion, a character or concept will appear in a series of one-shots, in cases where the subject matter is not financially lucrative enough to merit an ongoing or limited series, but still popular enough to be published on a regular basis, often annually or quarterly. A current example of a series of one-shots would be Marvel Comics' Franklin Richards: Son of a Genius publications. This type of one-shot is not to be confused with a comic book annual, which is typically a companion publication to an established ongoing series.
The term has also been borrowed into the Franco-Belgian comics industry, with basically the same meaning, although there, it mostly refers to albums.
In the Japanese manga industry, the same concept is expressed by the term yomikiri (読み切り), which implies that the comic is presented in its entirety without any continuation. One-shot manga tells its entire story in 15-60 pages, usually written for contests, and sometimes later developed into a full-length manga series (much like a television pilot). Many popular manga series began as one-shot stories, these include Dragon Ball, Fist of the North Star, Naruto, Bleach, One Piece, Berserk, Kinnikuman and Death Note among others. Some noted manga authors, such as Akira Toriyama and Rumiko Takahashi, have worked on numerous one shot stories in addition to their serialized works. Rising Stars of Manga was an annual competition for original English-language one-shot manga, many of which have gone on to become full-length manga series.