The Piper J-3 Cub is an American light aircraft built between 1937 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 almost 20,000 built in the United States.

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 airplane's standard chrome yellow paint has come to be known as "Cub Yellow".

Many original Cubs are flying today, and modernized versions of the Cub are still produced, both as bush planes and for nostalgic value.