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

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 2014 PN70, a New Horizons flyby candidate

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

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

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

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)