The IRB 2015 Rugby World Cup was the eighth Rugby World Cup, the quadrennial rugby union world championship. The tournament was hosted by England from 18 September to 31 October. Of the 20 countries competing in the World Cup in 2011, there was only one change: Uruguay replaced Russia. This was the first World Cup with no new teams to the tournament.

Reigning champions New Zealand won the cup and defended their title by defeating Australia 34–17 in the final; South Africa defeated Argentina to take third place. This was the first Rugby World Cup where no Northern Hemisphere team got beyond the quarter-finals. New Zealand were the first team to retain their title and the first to win for a third time.

The highly contested match between Japan and South Africa on the opening weekend, in which Japan scored the winning try in the final minute, was widely considered the biggest upset in the history of rugby. Hosts England were eliminated at the pool stage, after defeats by Wales and Australia; this was the first time the knockout stage did not feature a host nation.