G1

G1, G01, G.I, G-1, or G One may refer to:

Science and technology

 * G1 phase, in the cellular cycle
 * G1 regulatory sequence for the insulin gene
 * ATC code G01 Gynecological antiinfectives and antiseptics, a subgroup of the Anatomical Therapeutic Chemical Classification System
 * Alkali metal, Group 1 of the periodic table
 * G1, an informal group of fossil bird eggs from the Gobi desert that were later named Gobioolithus minor

Astronomy

 * Globular cluster Mayall II
 * YGKOW G1, a giant elliptical galaxy that lensed the Twin Quasar
 * G1 star, a subclass of G-class stars
 * G1, a cloud that passed by Sagittarius A* around 2001-2002
 * g1, temporary designation of minor planet, a New Horizons flyby candidate

Computing

 * Garbage-first collector, of the Oracle HotSpot Java virtual machine
 * G1, in ISO 2022 character sets, one of 4 groups of characters that may be swapped into the encoding space via control codes

Cameras

 * Contax G1, a Rangefinder camera made by Contax
 * DSC-G1, a 2007 Sony Cyber-shot G series camera model
 * PowerShot G1, a Canon camera
 * Panasonic Lumix DMC-G1, a digital camera made by Panasonic

Military

 * Ordnance QF 25 pounder (South African Army designation: G1)
 * G-1 (submarine), a class of early-20th century submarines constructed by the Lake Torpedo Boat Company of Bridgeport, Connecticut and purchased by the US Navy
 * Char G1, a French tank
 * G1, the designation used by the West German and Turkish armies for the FN FAL rifle
 * G.I, a German designation for several World War I heavy bombers:
 * AEG G.I
 * Albatros G.I, a German aircraft whose development was the Albatros G.II 1916 aircraft
 * Friedrichshafen G.I
 * Gotha G.I
 * Hansa-Brandenburg G.I, a 1916 bomber aircraft
 * Fokker G.I, a 1937 Dutch heavy twin-engined fighter plane
 * G-1 military flight jacket, a type of flight jacket
 * Kampfgeschwader 55 (historic Geschwaderkennung code G1), with the Luftwaffe in World War II

Sports

 * G1 Climax, an annual professional wrestling singles tournament held by New Japan Pro Wrestling
 * Group One, the highest level races in horseracing

Transportation

 * G1 Aviation G1, French ultralight aircraft
 * G1 Beijing–Harbin Expressway, in China
 * Alfa Romeo G1, a 1921 Italian car
 * Gorkha Airlines (IATA airline designator)
 * One of the G-series Toronto subway cars

Other uses

 * G1 (website), a Brazilian news portal owned by Grupo Globo
 * G1 Group, a Scottish hospitality and leisure operator
 * G1 licence, the first tier in the graduated licensing programme for Ontario's new drivers
 * G.One (character), an android super hero
 * Gangwon No.1 Broadcasting, a Seoul Broadcasting System television channel in Gangwon Province
 * Godzilla Minus One, a 2023 kaiju film often abbreviated to G–1
 * T-Mobile G1, the first publicly available Android smartphone
 * Transformers: Generation 1, a toy line which ran from 1984 to 1992
 * The Transformers (TV series), an animated television series meant to promote the toy line (popularly referred to as Generation 1)