Founded in 1959 by Jem Marsh and Frank Costin ("Mar" "Cos") Marcos built its first model, the GT, in 1960. Its most famous models have been based on the Volvo powered 1964 1800, later cars have used a variety of engines including Ford and Rover (V8) units. A notable feature of the early cars was the use of a Plywood chassis, although this feature disappeared a long-time ago.

The ill-conceived 1970 Mantis model led Marcos into financial trouble and the company ceased trading in 1971. Thankfully the name and basic design was revived in the 1980's and survives in low-volume production today.