Rugby league football is a full-contact team sport played with a prolate spheroid-shaped ball by two teams of thirteen on a rectangular grass field. Rugby league is one of the two major codes of rugby football, the other being rugby union. The league code is most prominent in Great Britain, Australia, New Zealand, and France, where the sport is played professionally. Rugby league is also immensely popular in Papua New Guinea where it is considered the national sport and many national players figure prominently in the Australian Rugby League. The game is played to a lesser extent in several other countries, such as Russia, the United States and Lebanon.

Rugby league takes its name from what was initially a breakaway faction of England's Rugby Football Union (RFU) known as the Northern Union when established in 1895. Both unions played rugby football under the same rules at first, until similar breakaway factions occurred from RFU-affiliated rugby unions in Australia and New Zealand in 1907 and 1908, and formed associations known as rugby football leagues, introducing modified Northern Union rules to create a new form of rugby football. The Northern Union later changed its name to the Rugby Football League in 1922 and thus, over time the sport itself became known as "rugby league". Over the following decades, the rules of both forms of rugby were gradually changed, and now rugby league and rugby union are distinctly different sports.