B1a

b1a may refer to:


 * Rockwell B-1A Lancer, U.S. USAF bomber aircraft
 * GSR Class B1a, a steam locomotive class
 * B1A section, a WWII counterespionage unit in the Double-Cross System (XX System)
 * B1a cells, a type of B1 cell
 * B1A postal code, see List of postal codes of Canada: B