B1

B1, B.I, B.1 or B-1 may refer to:

Biology and Chemistry

B-1 Lancer, a United States Air Force strategic bomber
B1 (New York City bus) serving Brooklyn
B1 type submarine, a WWII Imperial Japanese Navy submarine class
Alsace-Lorraine B 1, a Alsace-Lorraine P 1 class steam locomotive
Marussia B1, a high-performance luxury sports coupé built by Russian automaker Marussia Motors
GS&WR Class B1, a Great Southern and Western Railway Irish steam locomotive
HMS B1, a B-class submarine of the Royal Navy
LB&SCR B1 class, an 1882 British express passenger steam locomotive
LNER Thompson Class B1, a British steam locomotive
NCC Class B1, a Northern Counties Committee Irish steam locomotive
PRR B1 and PRR B1 (steam), two American PRR steam locomotives models
Saturn B-1, a 1959 four-stage rocket
USS B-1, a United States Navy B-class submarine
Brasilsat B1, a 1994 communication satellite
Char B1, a French heavy tank

B1, archive format
B-1 visa, issued by the United States to a foreign citizen seeking to enter the United States of America for business purposes
Brooklyn's Number One, a 1990's rapper from St Albans, Queens, United States appearing on the Kool G Rap's 4,5,6 1995 album
a subclass of B-class stars
an international standard paper size (707 × 1000 mm), defined in ISO 216
a level in the Common European Framework of Reference for Languages
a security class in the TCSEC
the code for permission to use specific land or premises for offices, light industry in town and country planning in the UK
a sentient banana in the children's TV series Bananas in Pyjamas