The Shelby Mustang is a high performance variant of the Ford Mustang

Ford Mustang

The Ford Mustang is an automobile manufactured by the Ford Motor Company. It was initially based on the second generation North American Ford Falcon, a compact car. Introduced early on April 17, 1964, as a "1964½" model, the 1965 Mustang was the automaker's most successful launch since the Model A...

 which was built by Shelby American from 1965 through 1970. Following the introduction of the fifth generation Ford Mustang, the Shelby nameplate was revived in 2007 for new high performance versions of the Mustang.
The 1965–1966 cars were the smallest and lightest of the GT 350 models. These cars are often improperly called "Cobras", which was the Ford-powered AC-based two-seat sports car

AC Cobra

The AC Cobra, also known colloquially as the Shelby Cobra in North America, is an Anglo-American sports car that was produced during the 1960s.-History and development:...

 also produced by Shelby American during the same period.