Not to be confused with
K0 (K followed by zero).
A KO is a knockout in various sports, such as boxing and martial arts.
K.O., Ko or Kō may also refer to:
Music
- KO (musician), Canadian musician who plays a fusion of hip hop and folk music
- K.O. (album), a 2021 album by Danna Paola
- K.O (rapper), South African rapper Ntokozo Mdluli
- Karen O (born 1978), lead singer of the rock group Yeah Yeah Yeahs
- Kevin Olusola, American cellist, beatboxer and member of a cappella group Pentatonix
- K.O. (song), a song by Pabllo Vittar
- K.O., a 2008 album by Rize
- "K.O.", a 2004 song by Smujji
- Ko (Korean surname)
- Gao (surname), a surname of Chinese origin romanized to Ko in Hong Kong, and in several romanizations especially in South-east Asia
- Ke (surname), a Chinese surname romanized as "Ko" in the Wade–Giles system
- Xu (surname 許), a surname of Chinese romanized as Ko in the Teochew dialect
- K.O (rapper) South African musician and businessman
- KO (musician), Canadian musician who plays a fusion of hip hop and folk music
- Ko Simpson (born 1983), professional American football player for the Buffalo Bills
- Kevin Owens, Canadian professional wrestler
- Ko Mountain, the second-highest peak in the Sikhote-Alin Mountains of Russia
- Ko. Madhepura, Nepal, a village development committee
- Ko, Lamphun, Thailand, a village and subdistrict
- Kö, an urban boulevard in Düsseldorf, Germany
- The Coca-Cola Company, stock ticker symbol and corporate internet domain ko.com
- Civic Coalition (Poland), or Koalicja Obywatelska (KO), a Polish electoral alliance
- Knock-off, a counterfeit product
- Kemetic Orthodoxy, a religion
- Contracting Officer, US government acronym KO or CO
- K.O., protagonist in OK K.O.! Let's Be Heroes
- Ko Ukumori, a character in the air combat game The Sky Crawlers: Innocent Aces
- Dukkha, the concept of unsatisfactoriness in Buddhism
- Kick-off (association football), the time or manner of start of play
- Kō, Japanese for incense; see Japanese incense
- Kōdō, the art of appreciating Japanese incense
- Momofuku Ko, a New York restaurant