59Fifty is a brand of hats made by the New Era Cap Company based in Buffalo, New York. They are often referred to as "Fitted Hats".^{[by whom?]} The caps are available for every Major and Minor League Baseball team in an assortment of colors, as well as NHL, NBA and NFL (Adidas normally manufactures the NBA's). The cap is also available with assorted city names and Marvel Comics and DC Comics character designs on them.

In 1992, the MLB New Era 59Fifty caps for the first time featured an MLB logo on the back of every cap. The New York Yankees were among the last teams in 1993 to wear the 59Fifty caps with the green underbrim. They didn't switch to the gray underbrim until 1994, whereas most teams switched to the gray underbrim during the late 1980s.

In 2007, New Era changed the design of their 59Fifty hats significantly. The 59Fifty is the official on-field cap for every major and minor league baseball team.