K1

K1, K.I, K01, K 1 or K-1 can mean:

;Military
* K1 Type 88, a modern main battle tank of the South Korean army
* Daewoo K1, a carbine of the South Korean army
* Fokker K.I, a WWI German experimental aircraft
* HMS Acanthus (K01) / HNoMS Andenes (K01), a 1939 British then Norwegian Royal Navy Flower class corvette
* K 1, a designation for a Swedish cavalry regiment

;Geography
* K1, another name for Masherbrum, a mountain in the Karakoram range in Pakistan
* K-1 (Kansas highway), a state highway in Kansas

;Names
* K1, an often used abbreviation of Keiichi Morisato's or Keiichi Maebara's first name (In the Japanese language 1 is "ichi")

;Vehicles / transportation
* K1, an abbreviation for single-person Sprint Kayak
* K-1 Attack, a slovak sports car
* K-1 Vehicle, an aerospace vehicle under development by Rocketplane Kistler
* BMW K1, a model of sport bikes
* Furness Railway K1, a steam locomotive related to the Furness Railway K2
* GSR Class K1, a Great Southern Railway Irish steam locomotive model
* LNER Thompson/Peppercorn Class K1, a 1949 British 2-6-0 (mogul) steam locomotive model
* London Buses route K1, a Transport for London contracted bus route
* NCC Class K1, a Northern Counties Committee Irish steam locomotive model
* PRR K1, an American model
* Tatra K1, a 1967 Czeckoslovakian experimental tramcar
* USS K-1 (SS-32), a 1913 United States Navy K class of submarine
* the first 1909 TGR K Class garratt, a type of articulated steam locomotive

;Electronics
* K1 Magnetophon, the first tape recorder, produced in Germany in 1935
* Motorola KRZR K1, a mobile phone
* Sendo K1, a Sendo mobile phone model

;United States forms
* K-1 visa, a United States immigration visa (also called the fiancé(e) visa)
* Schedule K-1, a tax form of the United States Internal Revenue Service (IRS) corresponding with Form 1065 to report one's share of income in a flow-through entity

;Miscellaneous
* K1, a Larcum Kendall Marine chronometer (1769)
* K-1, a type of kickboxing, martial arts, combat sport promoted by an organization of the same name
* K. 1, a designation for the works of two composers
* K1, an alternative title for Kommune 1
* k1, a coefficient that encapsulates process-related factors, limiting the minimum feature size in photolithography
* a abbreviation for
* Kingz1 a Cumbia music group.