9K

9K may refer to:
 * 9000 (number), the natural number following 8999 and preceding 9001
 * Gnome-Rhône 9K, a 9-cylinder 550 hp (405 kW) air-cooled radial engine
 * Cape Air IATA airline designator
 * Kuwait aircraft registration code
 * Kampfgeschwader 51, from its historic Geschwaderkennung code with the Luftwaffe in World War II
 * NY 9K, see New York State Route 9N
 * Soyuz 9K, see Soyuz-B
 * Yak 9K, see Yakovlev Yak-9
 * 9K, a model of SNECMA Atar
 * Typ 9K, a model of SEAT Inca
 * GCR Class 9K, a class of British 4-4-2T steam locomotive