The 1955, 1956, and 1957 are the Classic Thunderbird (T-Bird) by definition. They represent the original spirit of the Thunderbird: a luxury two-seater with the level of refinement and quality to compete against any European brand.

The Thunderbird known as the Square Bird was built between 1958 and 1960 as a transitional vehicle. The Thunderbird was growing up, becoming a two-door four-seater vehicle instead of the two-seater of the previous generation.

1961, 1962, 1963 Ford Thunderbird is sometimes called the "Bullet Bird" because of its shape. The Thunderbird, or T-Bird defines the classic American automobile.

The 1964, 1965, and 1966 Ford Thunderbirds are now classed the Flair Birds. These were the generation that completed the transition to the four seater T-bird.