The Piasecki H-21 Workhorse/Shawnee is an American helicopter, the fourth of a line of tandem rotor helicopters designed and built by Piasecki Helicopter. Commonly called "the flying banana", it was a multi-mission helicopter, capable of being fitted with wheels, skis or floats.

Piasecki Helicopter Corporation designed and manufactured helicopters in Philadelphia and nearby Morton, Pennsylvania, in the late 1940s and the 1950s. Its founder, Frank Piasecki, was ousted in 1956 and started a new company, Piasecki Aircraft. Piasecki Helicopter was renamed Vertol Corporation in early 1956. Vertol was acquired by Boeing in 1960 and renamed Boeing Vertol.