'''B4''', '''B04''', '''B.IV''' or '''B-4''' may refer to:
{{TOC right}} ==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<!--OK if first link red--> 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 * 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<!--OK if first link red--> 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== thumb|right|A painted B-4 bag * HMS ''B4'', a British B-class submarine of the Royal Navy * Keystone B-4, a United States Army Air Corps biplane bomber * SM ''UB-4'', a 1915 German U-boat * 203-mm howitzer M1931 (B-4, "Stalins Hammer"), a World War II Soviet ordnance piece * B-4 a US Air Force/USAAF 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) <!-- because B IV etc. redirect here -->
{{Letter-Number Combination Disambiguation}}