B21 may refer to:
Places Kepong–Selayang Highway (Selangor state route B21), Malaysia Autovía B-21, Spain; a motorway Harumi Chūō (station code B21), Tokyo BRT, Tokyo, Japan Mikamo Station (station code B21), Higashimiyoshi, Miyoshi, Tokushima, Japan; a train station Shin-Hōsono Station (station code B21), Seika, Kyoto, Japan; a train station Sugarloaf Regional Airport (FAA airport code B21), Franklin County, Maine, USA
Transportation and vehicular B21 (New York City bus), a bus route serving Brooklyn, New York City, New York State, USA Unterseeboot B-21, a WW1 German submarine
Automotive BSA B21 (1937–1939), a British motorcycle made by Birmingham Small Arms Company, Birmingham, England Leyland B21 (1979–1985), a bus chassis manufactured by Leyland Volvo Redblock Engine (B21), an automotive engine Chevron B21, a racing prototype Group 5 sports car built by Chevron Cars Ltd
Aviation Northrop Grumman B-21 Raider, a 21st-century American stealth bomber North American XB-21 ("B-21"), an experimental bomber aircraft developed in the late 1930s B.21/35, British interwar twin-engined bomber
Arts, entertainment, media B. 21 (), a Czech comic opera by Dvorak B21 (band), a British bhangra group
Other uses B-21 (machine), a cypher machine invented by Boris Hagelin Burroughs B21, a variant of the Burroughs B20 microcomputer HLA-B21, an HLA - B serotype Boron-21 (B-21 or 21B), an isotope of boron B21, a nuclear reactor at Dungeness nuclear power stations, Dungeness headland, southern Kent, England, UK
See also
Must B 21, a 2003 album by American singer will.i.am 21B (disambiguation)