Diablo III is a hack-and-slash action role-playing game developed and published by Blizzard Entertainment as the third installment in the Diablo franchise. It was released for Microsoft Windows and OS X in May 2012, the PlayStation 3 and Xbox 360 in September 2013, the PlayStation 4 and Xbox One in August 2014, and the Nintendo Switch in November 2018. Players choose to play as one of seven character classes – Barbarian, Crusader, Demon Hunter, Monk, Necromancer, Witch Doctor, or Wizard – and are tasked with defeating the Lord of Terror, Diablo, as in previous games in the series.

An expansion pack entitled Reaper of Souls was released for PC in March 2014. It was released for consoles as part of the Diablo III: Ultimate Evil Edition version in August 2014. The Rise of the Necromancer pack was released for the Windows, macOS, and PlayStation 4 and Xbox One in June 2017. Diablo III: Eternal Collection, combining Reaper of Souls and Rise of the Necromancer, was released for PlayStation 4 and Xbox One in June 2017, and for the Nintendo Switch in November 2018.

The game received critical acclaim, although its always-on DRM feature was criticized. The game set a new record for "fastest-selling PC game" by selling over 3.5 million copies in the first 24 hours of its release, and became the best-selling PC game of 2012 by selling over 12 million copies. As of August 2015, the number of sales had grown to over 30 million.