Frederick (Frits) Koolhoven (11 January 1886 – 1 July 1946) was an aircraft designer in Britain and his native Netherlands.
Koolhoven was born in Bloemendaal, Netherlands. After training as an engineer in Liège and Antwerp, he worked from 1907 as a mechanical engineer for Minerva in Antwerp, and also drove in races and rallies for them. He became interested in aviation. In 1910 he acquired his own Hanriot aircraft, and was involved in the construction of the first Dutch plane the "Heidevogel"
He designed many aircraft, initially in England from 1912 for British Deperdussin, then from 1914 for Armstrong Whitworth Aircraft, then from 1917 as chief designer for the British Aerial Transport Company alongside the Dutch chief draughtsman Robert B.C. Noorduyn.
He returned to the Netherlands, but there the market was dominated by Fokker, so he returned to his old job as an automobile engineer for the Spyker automobile factory.
In 1921, a group of businessmen founded the Nationale Vliegtuig