Ket or KET may refer to:

• The right part of bra–ket notation,
• Ket (software), an algebra editor

• KET, an American public TV network
• Ket vallomas (lit. 'Two Confessions'), a 1957 Hungarian film

• Ket (Greyhawk), a fictional nation in Dungeons and Dragons
• Cet mac Mágach, of Irish myth
• Ket and Wig, from the Danish history Gesta Danorum
• A name of the Celtic mythic figure Ceridwen

• Ket people (or Yenisei Ostyaks), of Siberia
• Ket Sivan (born 1981), Cambodian swimmer

• Ket (river), Siberia
• Keť, Slovakia
• Kettering railway station, England (code:KET)
• Kengtung Airport, Myanmar (IATA:KET)
• Kennedy Town station, Hong Kong, China (MTR:KET)

• Ket language, spoken in Siberia
• Ketamine, a dissociative anaesthetic drug
• Key English Test, an international exam

• Kit (disambiguation)