The Louisville Colonels were a Major League Baseball team that also played in the American Association (AA) throughout that league's ten-year existence from 1882 until 1891. They were known as the Louisville Eclipse from 1882 to 1884, and as the Louisville Colonels from 1885 to 1891; the latter name derived from the historic title of the Kentucky Colonel. After the AA folded in 1891, the Colonels joined the National League and played through the 1899 season.

In the sport of baseball, a doubleheader is a set of two games played between the same two teams on the same day. Historically, doubleheaders have been played in immediate succession, in front of the same crowd. Contemporarily, the term is also used to refer to two games played between two teams in a single day in front of different crowds and not in immediate succession.