Rocketdyne
The Rocketdyne Division was founded by North American Aviation (NAA) in 1955, and was later part of Rockwell International (1967-1996) and Boeing (1996-2005). In 2005, the Rocketdyne Division was sold to United Technologies Corporation, becoming Pratt & Whitney Rocketdyne as part of Pratt & Whitney. In 2013, Pratt & Whitney Rocketdyne was sold to GenCorp, which merged it with Aerojet to form Aerojet Rocketdyne.
SpaceX
Since the founding of SpaceX in 2002, the company has developed three families of rocket engines — Merlin and the retired Kestrel for launch vehicle propulsion, and the Draco control thrusters. SpaceX is currently developing two further rocket engines: SuperDraco and Raptor. SpaceX is currently the world’s most prolific producer of liquid fuel rocket engines.