B3

B3, B03, B.III or B-3 may refer to:

American bombers

 * Keystone B-3, a biplane bomber of the United States Army Air Corps
 * Next-Generation Bomber (2018 Bomber), next bomber follow-on to the B-2 stealth bomber program
 * Long Range Strike Bomber program, successor program to the 2018 Bomber program
 * Northrop Grumman B-21, a successor aircraft to the B-1 and B-52 bombers

German and Austro-Hungarian aircraft

 * AEG B.III, a German reconnaissance aircraft
 * Albatros B.III, a German Idflieg B-class designation aircraft
 * Aviatik B.III, a 1916 Austro-Hungarian reconnaissance aircraft
 * Euler B.III, a German Idflieg B-class designation aircraft
 * Fokker B.III (disambiguation), two aircraft models
 * Halberstadt B.III, a German Idflieg B-class designation aircraft
 * Kampfgeschwader 54, from its historic Geschwaderkennung code with the Luftwaffe in World War II
 * Lohner B.III
 * LVG B.III, a 1910s German two-seat trainer biplane

Submarines

 * USS B-3 (SS-12), a United States Navy submarine
 * HMS B3, a British B class submarine of the Royal Navy

Roads

 * B3 road (Kenya)
 * B3 road (Namibia)
 * Bundesstraße 3, a German national highway

Trains

 * Alsace-Lorraine B 3, an Alsace-Lorraine P 1 class steam locomotive
 * Bavarian B III, an 1852 German steam locomotive model
 * NCC Class B3, an 1890 Irish 4-4-0 passenger steam locomotive
 * NSB B3 (Class 3), Norwegian railway carriages
 * LNER Class B3, a British locomotive class

Other

 * B3 (New York City bus) serving Brooklyn
 * Bellview Airlines (International Air Transport Association code B3)

Biology and medicine

 * B3 (classification), a medical-based Paralympic disability sport classification for blind sport
 * B3 domain, a highly conserved plant DNA-binding domain
 * Procyanidin B3, a plant phenolic compound
 * ATC code B03 Antianemic preparations, a subgroup of the Anatomical Therapeutic Chemical Classification System
 * Prodelphinidin B3, a plant phenolic compound
 * Vitamin B3 (niacin)

Computing

 * A TCSEC security class in the Trusted Computer System Evaluation Criteria
 * "B3 Coin" a cryptocurrency

Engines

 * A type of four-cylinder Mazda B engine
 * Benz B.III, an engine powering the 1914 Friedrichshafen FF.33 German aircraft

Music

 * B3 (band), an American boy band most popular in Germany
 * B3 (EP), a 2012 EP by alternative rock band Placebo
 * Hammond B-3, an electric organ

Other uses

 * B3 (stock exchange)
 * $$B_3^I$$, the Bochvar logic in calculus
 * B03, Alekhine's Defence chess code
 * B3: Battle by the Bay, a 1996 Street Fighter tournament
 * B3 oil field, an oil and gas field in the Baltic sea
 * Model B3 chair, a 1925 German Wassili designer chair
 * A subclass of B-class stars in stellar classification
 * a permission code for Town and country planning in the United Kingdom
 * An ISO 216 international standard that defines paper size
 * B3 the chemical formula for triboracyclopropenyl