KSI (disambiguation)
KSI (born 1993; Olajide Olatunji) is a British YouTube personality, musician and professional boxer.
KSI or Ksi may also refer to:
- Killed or seriously injured, in road safety
- Kontoret för särskild inhämtning ("Office for Special Collection"), a Swedish intelligence agency
- The Korean Studies Institute, a research institution on Korean studies in South Korea
- KSI Industries, a fictional company in Transformers: Age of Extinction
- KSI, IATA code for Kissidougou Airport in Guinea
- Icelandic: Knattspyrnusamband Íslands (Football Association of Iceland), Icelandic sports group
- ksi (unit), kilopound per square inch, a non-SI unit of stress or pressure
- Ksi (Cyrillic), a letter of the early Cyrillic alphabet (Ѯ, ѯ) derived from the Greek letter Xi