B4, B04, B.IV or B-4 may refer to:
Transportation
Aviation B4, IATA code of BeOnd, an airline based in Malé, Maldives B4, IATA code of B.A.C.H. Flugbetrieb, an Austrian charter airline (ICAO code BCF) B4, IATA code of Bankair, a US American charter airline (ICAO code BKA) B4, then-IATA code of Flyglobespan, a former British airline Auster B.4, 1951 British light transport aircraft with rear ramp Bensen B-4, Bensen Aircraft autogyro Bäumer B IV Sausewind, German 1920s sports aircraft Fokker B.IV, parent company's designation for American branch's F.11 seaplane Hawker B 4, Swedish designation for Hawker Hart biplane Keystone B-4, United States biplane bomber Lohner B.IV, an Austro-Hungarian World War 1 reconnaissance biplane Pilatus B-4, Swiss glider also designated PC-11.
Locomotives Alsace-Lorraine B 4, an Alsace-Lorraine P 1 class steam locomotive Bavarian B IV, an 1852 German steam locomotive Ceylon Government Railway B4 GSR Class B4, a former Cork, Bandon and South Coast Railway steam locomotive of the Great Southern Railways, Ireland LSWR B4 class, an 1891 British dock tank locomotive PRR B4, an American Pennsylvania Railroad steam locomotive Soo Line B-4 class, an American 0-6-0 steam locomotive LB&SCR B4 class, a British tender locomotive class LNER Class B4, a British class of locomotives
Automotive uses Subaru B4, the name under which the Subaru Legacy is marketed in Israel B4 (New York City bus), serving Brooklyn B4 road (Namibia) Bundesstraße 4, federal highway in Germany Alpina B4, a German sports executive car
In the military
, a B-class submarine of the British Royal Navy Keystone B-4, a United States Army Air Corps biplane bomber SM UB-4, a 1915 German U-boat , a Spanish Navy submarine 203-mm howitzer M1931 (B-4), also known as "Stalin's Hammer", a World War II Soviet ordnance piece B-4 a United States Army Air Forces and United States Air Force flight bag A level of vehicle armour
In science Leukotriene B4 receptor and Leukotriene B4 receptor 2, two human genes Lipoxin B4, a lipoxin Proanthocyanidin B4, a B type proanthocyanidin Vitamin B4, an alternate name for adenine A stellar classification
In entertainment B4 (music show), a defunct British music video show broadcast on Channel 4 B4 (TV channel), a defunct British music television channel B-4 (Star Trek), an android in the Star Trek fictional universe Babylon 4 space station, predecessor to Babylon 5 from the Babylon 5 television series The Lost City (B4), a Dungeons & Dragons adventure module
Other uses B4 (classification), a parasports classification for visually impaired athletes B4 Street Fighter Championships, a 2000 fighting game tournament B4 or B4 II, a Native Instruments virtual synthesizer for Hammond organ (B-3) sound emulation B4-mount, used for professional video cameras such as Betacam An international standard paper size (250×353 mm), defined in ISO 216 B04, Alekhine's Defence chess code 1. b4, Sokolsky Opening in chess
See also 4B (disambiguation) Before (disambiguation) BIV (disambiguation)