Doubleheader is the term used to describe two baseball games played between the same two teams on the same day.

A doubleheader is usually the result of a game postponed due to inclement weather. Quite often the game is rescheduled for a day on which the two teams play each other again. In some cases, this may be weeks or months after the original date.

There are two types of doubleheader games, day-night and twi-night doubleheaders. A day-night doubleheader is one in which the first game is played in the early afternoon and the other is played at night. In a twi-night doubleheader, the first game is played in the twilight, or late afternoon.

The term doubleheader has also been expanded by network television to refer to two games of any sport aired back-to-back on the same network, even if they do not involve the same two teams. Three such games may be referred to as a tripleheader.