The P-3 Orion, originally designated P3V, based on the Lockheed L-188 Electra, which met limited success as a turboprop airliner competing against emerging pure jets. It served as the replacement for the post-war era P-2 Neptune.

The Orion is powered by 4 turboprops which give it a speed comparable to fast propeller powered fighters, or even slow turbofan jets such as the A-10. Most other similar patrol aircraft use this model, with Soviets adapting their own counterpart to the Electra.

The P-3 also competes with the British Nimrod adaptation of the Comet and the French Breguet Atlantique. Experience with the P-3 helped with the S-3 Viking carrier-borne ASW jet.

The P-3 has an internal bomb bay under the front fuselage, as well as under wing stations which can carry missiles such as the AGM-84 Harpoon. It has a long 'stinger' in the tail which houses the magnetic anomaly detector (MAD), and convex windows for observation. Sonobuoys can be dropped from externally loaded tubes (P-3C and later) or from inside the fuselage (A/B variants).

The first production version, designated P3V-1, first flew 15 April 1961, but by the time the first deliveries were made in 1962, the unified designation system made this the P-3. Paint schemes have changed from overall post-war blue, to 1960s white and grey, and 1980s low visibility grey.

Over the years many variants have been developed. The technology of the P-3 is similar to the larger, slower, and more successful C-130 Hercules transport. Similar versions have been developed for hurricane hunting, and aerial surveillance with a rotodome adapted from the E-2 Hawkeye. Despite higher performance, the P-3 has not been adapted into gunship or ground attack precision attack platform, aerial refuelling tanker, or attempted a carrier landing like the C-130.