KSI

• Knight Companion of the Order of the Star of India
• Key Success Indicator, another name for a key performance indicator
• Killed or Seriously Injured, used in the field of road safety
• ksi (unit), kilopound per square inch, a unit of stress or pressure
• Kontoret för Särskild Inhämtning, Office for Special Assignments, Swedish intelligence agency
• the IATA code for Kissidougou airport
• The Icelandic of Football Association of Iceland, KSÍ (Icelandic: Knattspyrnusamband Íslands)
• Kerr Scientific Instruments - A manufacturer of electrophysiology equipment
• Korea Sustainability Index - The corporate social responsibility index which measures Korean firms' sustainability level based on ISO 26000
• KSIOlajidebt, or Olajide 'JJ' Olatunji, an English-born Nigerian teenager who creates comedic FIFA videos on his YouTube channel. He resides in Berkhamsted, near Watford and is also an Arsenal F.C. supporter. He is most famously known for his video post on Emile Heskey which has acquired over 1 million views. His YouTube account was temporarily removed for offensive behaviour however has since been reinstated. His channel includes features such as "Beast Players," "FIFA funnies," "Race to division one," "let's talk FIFA 12," as well as live commentaries and game play. He acquired fame for repeated quotation of phrases such as "a rather fast black man," "Heskey" and "what you gonna' do?" He has a well known rivalry/ friendship with fellow x-box player calfreezy. Calfreezy has appeared in 5 KSI videos and most popularly in "race to division one" where calfreezy went "mental"

• Ksi (Cyrillic letter)
• pronunciation of Xi (letter)
• The Halo 2 clan, KSI.