E4

E4, E.IV or E-4 may refer to:

In entertainment:

* E4 (channel), a digital television channel in the United Kingdom and Ireland
* Every Extend Extra Extreme a video game from Q Entertainment
* Entertainment for All video game expo

In transportation :
* The IATA code for Aero Asia International airline

roads:
* E4 National Highway, a National Highways of Pakistan
* European route E4, a road through Finland and Sweden

Trains:
* E4 Series Shinkansen, a Japanese high-speed train
* CNW Class E-4, a 4-6-4 steam locomotive of the Chicago & Northwestern Railway
* EMD E4, a diesel locomotive
* LB&SCR E4 Class, a steam locomotive of the London, Brighton & South Coast Railway
* LNER E4 Class, a 2-4-0 steam locomotive built by the Great Eastern Railway and operated by the LNER
* PRR E4, an American

in military:
* Boeing E-4, a U.S. military flying command post
* Fokker E.IV, a 1915 German fighter aircraft
* The fourth enlisted rank in the Military of the United States, including
** Petty Officer Third Class in the United States Navy and United States Coast Guard
** Senior Airman in the United States Air Force
** Specialist (rank) in the United States Army (if the soldier is not a non-commissioned officer)
** Corporal in the United States Army and United States Marine Corps (if the soldier is a non-commissioned officer)

Other:
* E-4 process, an obsolete development process associate with photographic transparency film
* Honda E4, a predecessor of Honda's ASIMO robot
* Leukotriene E4, a naturally produced eicosanoid lipid mediator
* London E4, a postcode for Chingford
* King's Pawn Game, or 1. e4, a chess opening move
* Every Extend Extra Extreme, a video game