F9

F9, F09, F.IX, F 9 or F-9 can be one of:
* F-9 Cougar, an aircraft carrier-based version of the F9F Panther
* F-9 Flying Fortress, a reconnaissance variant of the B-17 Flying Fortress
* F 9 Säve, a former Swedish Air Force wing
* F9 visual arts
* EMD F9, a locomotive
* Fokker F.IX, a 1929 Dutch airliner
* LSWR F9 class, a British and also :
* F9F Panther, a United States Navy fighter aircraft in the Korean War
* F9C Sparrowhawk, a biplane parasite fighter from the 1930s originally designed for airships
* Frontier Airlines, IATA airline designator
* Factor IX, a coagulation factor
* a function key on a computer keyboard
* F09 : Unspecified organic or symptomatic mental disorder code