KO One (traditional Chinese: 終極一班; simplified Chinese: 终极一班; pinyin: zhōng jí yī bān; lit. 'The Ultimate Class') is a 2005 Taiwanese drama starring Jiro Wang, Calvin Chen, Aaron Yan and Danson Tang. It was produced by Comic International Productions (可米國際影視事業股份有限公司) and Gala Television, it was first broadcast in Taiwan on cable TV Gala Television (GTV) Variety Show/CH 28 (八大綜合台) on November 26, 2005 to May 27, 2006.

Before this drama was aired there was not much interest in it, due to the storyline and unfamiliar cast. Despite the new encounters, the ratings of KO One exceeded expectations. Although the ratings were not high, it brought fame to three of the four leads (Jiro Wang, Calvin Chen, Aaron Yan), who are part of the then newly formed Taiwanese boy band called Fahrenheit. This drama also brought fame to the Taiwanese artist, Tank who wrote and sang the opening and ending theme songs. The KO One original soundtrack was the best selling soundtrack of 2013, selling more than 60,000 copies in Taiwan within the first month of release.

On December 26, 2012, a new series is released at the same time on GTV, named KO One Return, which continues the story of KO One.