The Mikoyan-Gurevich MiG-21 is a supersonic jet fighter and interceptor aircraft, designed by the Mikoyan-Gurevich Design Bureau in the Soviet Union. Its nicknames include: "balalaika", because its planform resembles the stringed musical instrument of the same name; "Ołówek", Polish for "pencil", due to the shape of its fuselage, and "Én Bạc", meaning "silver swallow", in Vietnamese.

Approximately 60 countries across four continents have flown the MiG-21, and it still serves many nations six decades after its maiden flight. It set aviation records, becoming the most-produced supersonic jet aircraft in aviation history, the most-produced combat aircraft since the Korean War and, previously, the longest production run of any combat aircraft.