Michael Gregor, born Mikheil Grigorashvili (Georgian: მიხეილ გრიგორაშვილი) or Mikhail Leontyevich Grigorashvili (Russian: Михаил Леонтьевич Григорашвили) (1888 – 1953) was an aircraft engineer of Georgian origin, one of the pioneering aviators in the Russian Empire, the United States, and Canada.
Born in Derbent, Russia, Grigorashvili graduated from the Imperial Institute of Communications in St. Petersburg and was trained as a pilot in France in 1911.
Upon his return to Russia, Grigorashvili worked as an instructor for pilots and joined the army as an officer in World War I. The Bolshevik coup in 1917 forced him to retire to a newly independent Georgia where he worked as a road engineer in the Georgian ministry for communications.
After the Soviet takeover of Georgia in 1921, he went in exile to the United States where he would naturalize in 1926. Having briefly worked for a minor aviation factory in Rhode Island, Grigorashvili, by then known as Gregor, was recruited as an aircraft designer by the Dayton-Wright Company in 1921 and Curtiss-Wright in 1923. In 1934, Gregor founded his own firm Gregor Aircraft which constructed an original light plane 1GR-1.
Two years later, Gregor was employed by the Canadian Car and Foundry and designed FDB-1 biplane fighter. Despite being an advanced and innovative design, incorporating all-metal construction with flush riveting, retractable undercarriage and a sleek shape, the FDB-I was overtaken by events and, after being unable to find a buyer, was lost in a fire in 1945.