Parker Hannifin Corporation, originally Parker Appliance Company, usually referred to as just Parker, is an American corporation specializing in motion and control technologies. Its corporate headquarters are in Mayfield Heights, Ohio, in Greater Cleveland (with a Cleveland mailing address). The company was founded in 1917 and has been publicly traded on the NYSE since December 9, 1964. The firm is one of the largest companies in the world in motion control technologies, including aerospace, climate control, electromechanical, filtration, fluid and gas handling, hydraulics, pneumatics, process control, and sealing and shielding. Parker employs about 58,000 people globally.

Parker Hannifin's aerospace division, Parker Aerospace, designs and manufactures aerospace hydraulic equipment. It is a provider of aircraft parts to aircraft manufacturers, including fuel system components and high-temperature bleed air valves.