USS Akron (ZRS-4) was a helium-filled rigid airship of the U.S. Navy, the lead ship of her class, which operated between September 1931 and April 1933. She was the world's first purpose-built flying aircraft carrier, carrying F9C Sparrowhawk fighter planes, which could be launched and recovered while she was in flight. With an overall length of 785 ft (239 m), Akron and her sister ship Macon were among the largest flying objects ever built. Although LZ 129 Hindenburg and LZ 130 Graf Zeppelin II were some 18 ft (5.5 m) longer and slightly more voluminous, the two German airships were filled with hydrogen and so the US Navy craft still holds the world record for helium-filled airships.

Akron was destroyed in a thunderstorm off the coast of New Jersey on the morning of 4 April 1933, killing 73 of the 76 crewmen and passengers. The accident involved the greatest loss of life in any airship crash.

The airship's skeleton was built of the new lightweight alloy duralumin 17-SRT. The frame introduced several novel features compared with traditional Zeppelin designs. Rather than being single-girder diamond trusses with radial wire bracing, the main rings of Akron were self-supporting deep frames: triangular Warren trusses 'curled' round to form a ring. Though much heavier than conventional rings, the deep rings promised to be much stronger, a significant attraction to the navy after the in-flight break up of the earlier conventional airships R38/ZR-2 and ZR-1 Shenandoah. The inherent strength of these frames allowed the chief designer, Karl Arnstein, to dispense with the internal cruciform structure used by Zeppelin to support the fins of their ships. Instead, the fins of Akron were cantilevered: mounted entirely externally to the main structure. Graf Zeppelin, Graf Zeppelin II, and Hindenburg used a supplementary axial keel along the hull centerline. However, the Akron used three keels, one running along the top of the hull and one each side, 45 degrees up from the lower centreline. Each keel provided a walkway running almost the entire length of the ship. The electric and telephone wiring, control cables, 110 fuel tanks, 44 water ballast bags, 8 engine rooms, engines, transmissions, and water-recovery devices were placed along the lower keels. Helium, instead of flammable hydrogen, allowed the engines to be placed inside the hull, improving streamlining. A generator room, with 2 Westinghouse d.c. generators powered by a 30-h.p. internal combustion engine, was forward of the No. 7 engine room.