G4 or G.IV may refer to:

Transport

AEG G.IV The AEG G.IV was a biplane bomber aircraft used in World War I by Germany. It was developed from the AEG G.III, with refinements to power, bomb-load and dimensions. Coming into service in late 1916, it featured a bomb capacity twice as large as t ...

, a German World War I heavy bomber * Allegiant Air, by IATA airline designator *

Caudron G.4 The Caudron G.4 was a French biplane with twin engines, widely used during World War I as a bomber. It was designed by René and Gaston Caudron as an improvement over their single-engined Caudron G.3. The aircraft employed wing warping for ban ...

, a 1915 French biplane *

Friedrichshafen G.IV The Friedrichshafen G.IV and G.V (factory designations FF.61 and FF.55) respectively were heavy bombers that were designed and manufactured in Germany during World War I by Flugzeugbau Friedrichshafen. The G.IV saw limited use by the ''Luftstreit ...

, a 1918 German medium bomber * Gotha G.IV, a 1916 German heavy bomber * Gulfstream IV, a family of private jet aircraft * Mitsubishi G4M "Betty", a World War II Japanese fast bomber * Soko G-4 Super Galeb, a jet trainer/light attack jet of Yugoslav origin * USS ''G4'' (SS-26), a 1914 G-class submarine of the United States Navy * County Route G4 (California), a county highway in Santa Clara County, California, USA *

G4 Beijing–Hong Kong and Macau Expressway The Beijing–Hong Kong and Macau Expressway (), designated as G4 and commonly referred to as the Jinggang'ao Expressway () is a -long expressway that connects the Chinese cities of Beijing and Shenzhen, in Guangdong province, at the border ...

, an expressway in China *

G4 (Taichung Metro) Songzhu () is a railway station and metro station located in Beitun District, Taichung, Taiwan. It is served by the Taiwan Railways Administration Taichung line and the Green Line (Taichung Metro), Green Line operated by Taichung Metro, connecte ...

, also known as Songzhu Station or Jiushe Station, a station under construction in the Taichung Metro *

G4-class freighter The G4 class is a series of five combination roll-on/roll-off cargo ships (ConRO) that are operated by the Atlantic Container Line (ACL) and entered service in the mid-2010s. They are named ''Atlantic Star'', ''Atlantic Sail'', ''Atlantic Sea'', ...

, a cargo ship design

Biology

* G4 EA H1N1, a strain of influenza * G-quadruplex, a DNA secondary structure

Science and technology

* Group 4 element, a class of elements on the Periodic Table * ATC code G04 ''Urologicals'', a subgroup of the Anatomical Therapeutic Chemical Classification System * G4, a type of bi-pin lamp base (socket), a lamp fitting where the pin spacing is 4mm * LG G4 smartphone * Moto G4, a line of smartphones * Group 4 compression, a type of image compression used in fax machines and some image file formats

Apple Computer

* PowerPC G4, a type of microprocessor by Freescale used by Apple ** Power Mac G4, a series of personal computers made by Apple Inc in July 1999 ** PowerBook G4, a series of Professional notebooks made by Apple Inc in 2001 ** iMac G4, a series of personal computer made by Apple Inc in January 2002 ** Xserve G4, an Xserve server made by Apple Inc in May 2002 ** iBook G4, an iBook series of consumer notebooks in October 2003 ** Mac Mini G4, a Mac Mini series of ultracompact computer in January 2005

Entertainment

* G4 (American TV network), an American television channel * G4 (Canadian TV channel), a former Canadian television channel * G4 (band), a British vocal troupe *

Grob's attack Grob's Attack is an unconventional chess opening in which White begins with the move: :1. g4 It is widely considered to be one of the worst possible first moves for White. International Master John Watson writes, "As far as I can tell, 1 g4 i ...

, an opening move in chess

Organisations

* G4 nations, four nations that support each other's bids to become permanent members of the United Nations Security Council: Brazil, Germany, India, and Japan * Big Four (Western Europe), sometimes called 'G4', a group of powerful countries in Europe *

VIP Protection Unit The VIP Protection Unit (Abbreviation: VIPPU; ), otherwise known as G4 (originally Section G, Division 4) is a branch of the Hong Kong Police Force. Introduction The original name had been given to the unit since it is the 4th division of the ...