The Caproni Ca.165 was an Italian biplane fighter developed just before World War II, but produced only as a prototype, as the competing Fiat CR.42 Falco was selected for series production.

The engine was a V-12 671 kW (900 hp) Isotta Fraschini L.121 R.C.40 driving a three-bladed Alfa Romeo electric propeller.

After several modifications, the Ca.165 had the tail surface augmented and the aft fuselage lowered to fit a canopy with 360° visibility.

In any case, both engines were far from being sufficiently reliable and were never adopted in large numbers by the Italian air force.

Perhaps the influence of Fiat contributed to the selection of the CR.42 Falco over the Ca.165, although Caproni was an influential company itself at the time.

Apparently the bottom line was that the Ca.165's engine was much less reliable and only 44 kW (60 hp) more powerful, while the aircraft itself was 200 kg (440 lb) heavier.

Apparently, test pilots flying the Ca.165 managed to outperform the Falco but disliked the aircraft itself.

The faster speed was a more modern concept for a new generation fighter (especially in the interception of fast bombers such as the Bristol Blenheim, which often proved too fast for the Falco), and speed was an increasingly important design consideration in World War II-era aircraft.