B9

B9, B IX or B-9 may refer to:
* B9 (Croatia), a part of the Istrian Y highway complex in Croatia
* B9 (New York City bus) serving Brooklyn
* B9 road (Cyprus)
* Bavarian B IX, a 1874 German steam locomotive model
* Bavarian B IX (Ostbahn), a 1869 German steam locomotive model
* Bensen B-9, a 1958 American small helicopter
* Boeing B-9, a 1931 all-metal monoplane bomber aircraft designed for the United States Army Air Corps
* HMS B9, a B-class submarine of the Royal Navy
* Iceberg B-9, a 1987 iceberg calved away from Antarctica
* Model B-9, otherwise known simply as "Robot" on the TV series Lost in Space
* Vitamin B9, another name for the folic acidand also :
* the abbreviation used for the record label Bridge Nine
* the former model name for the Subaru Tribeca
* the IATA code for Air Bangladesh
* the IATA code for Iranair Tours
* a subclass of B-class stars
* The Boeing Y1B-9, a bomber of the United States Army Air Corps
* an international standard paper size (44×62 mm), defined in ISO 216