The Pontiac GTO is a front-engine, rear-drive, two-door, four- or five-passenger automobile manufactured and marketed by the Pontiac division of General Motors over four generations from 1963 until 1974 in the United States — with a fifth generation made by GM's Australian subsidiary, Holden, for the 2004 through 2006 model years.

The first generation of the GTO is credited with popularizing the muscle car market segment in the 1960s.[2][3] The Pontiac GTO is considered by some to have started the trend with all four domestic automakers offering a variety of competing models.[4][5]

For the 1964 and 1965 model years, the GTO was an optional package on the intermediate-sized Pontiac Lemans. The 1964 GTO vehicle identification number (VIN) started with 22, while the 1965 GTO VIN started with 237. The GTO became a separate model from 1966 through 1971 (VIN 242...). It became an optional package again for the 1972 and 1973 intermediate LeMans. For 1974, the GTO was an optional trim package on the compact-sized Ventura.

The GTO was selected as the Motor Trend Car of the Year in 1968.

The GTO model was revived from 2004 to 2006 model years as a captive import for Pontiac, a left-hand drive version of the Holden Monaro, itself a coupé variant of the Holden Commodore.