The Avia B.135 (RLM designation Av-135) was a Czechoslovak cantilever monoplane fighter aircraft.
It was the production version of the Avia B.35 developed shortly before the war, based on the B.35/3 prototype but featuring a new all-metal wing.
The B.135/1 prototype attracted the attention of Bulgarian Air Force officers visiting the Avia plant, and a production contract for 12 aircraft and 62 engines was signed, as well as a license to allow an additional 50 airframes to be constructed by DAR as the DAR 11.
However, the DAR facilities proved to be incapable of producing the aircraft, and only the 12 Czech-built examples were ever made.
Plans for further production were stopped by the RLM, which also interrupted engine deliveries after 35 units, and the Bulgarian Air Force was encouraged to purchase the Messerschmitt Bf 109 instead.