Kokusai Kogyo Kabushikigaisha, a Japanese bus and taxi company

Catechism of the Catholic Church, in German Katechismus der Katholischen Kirche, in Polish Katechizm Kościoła Katolickiego

Ku Klux Klan, white supremacy group(s)

A Scottish firm which sells falconry supplies: see http://www.falconclubs.fsnet.co.uk/KKK%20Scotland.htm

The Turkish Armed Forces, known in Turkish as Kara Kuvvetleri Komutanligi (KKK)

Kool Kids Klub, a promotional club for Kool Aid beverages

Kappa Kappa Kappa, a social fraternity

Kinder, Küche, Kirche, German slogan

Kokusai Kōryū Kikin, or the Japan Foundation

Kalmyk Kavallerie Korps, see Kalmykian Voluntary Cavalry Corps

Katipunan ("Society"), a revolutionary group from Philippine history; full name Kataastaasang Kagalanggalangang Katipunan ng mga Anak ng Bayan (roughly translated: "Supreme and Venerable Society of the Sons of the Nation")

AG Kühnle, Kopp & Kausch, a turbine manufacturer from Germany, since 21 November 2006 a part of Siemens Power Generation.

Kernkraftwerk Krümmel, a nuclear power plant in Germany