The Piper J-3 Cub is an American light aircraft that was built between 1938 and 1947 by Piper Aircraft. The aircraft has a simple, lightweight design which gives it good low-speed handling properties and short-field performance. The Cub is Piper Aircraft's most-produced model, with nearly 20,000 built in the United States. Its simplicity, affordability and popularity invokes comparisons to the Ford Model T automobile.

The aircraft is a high-wing, strut-braced monoplane with a large-area rectangular wing. It is most often powered by an air-cooled, flat-4 piston engine driving a fixed-pitch propeller. Its fuselage is a welded steel frame covered in fabric, seating two people in tandem.

The Cub was designed as a trainer. It had great popularity in this role and as a general aviation aircraft. Due to its performance, it was well suited for a variety of military uses such as reconnaissance, liaison and ground control. It was produced in large numbers during World War IIas the L-4 Grasshopper. Many Cubs are still flying today. Cubs are highly prized as bush aircraft. The aircraft's standard chrome yellow paint came to be known as "Cub Yellow" or "Lock Haven Yellow".