The Alekseyev I-21 was a Soviet twin-engined jet fighter, built in the late 1940s. Two prototypes were constructed with the designation of I-211, of which one was converted into the I-215 with more powerful engines. A third aircraft was built to evaluate the bicycle landing gear arrangement for use in other aircraft. The fighter was not accepted for production as it was inferior to the swept-wing fighters like the Mikoyan-Gurevich MiG-15.