Diablo is an action role-playing hack and slash dungeon crawler video game series developed by Blizzard North and continued by Blizzard Entertainment after the north studio shutdown in 2005. The series is made up of three core games: Diablo, Diablo II, and Diablo III. Expansions include the third-party published Hellfire, which follows the first game, Lord of Destruction, published by Blizzard and released after the second game, and Reaper of Souls, which follows the third game. Additional content is provided through story elements explored in other media forms. Diablo IV was announced at BlizzCon 2019.

The games in the Diablo series have been well received by critics and were financial successes. Diablo II sold 4 million copies in the year it was released. Diablo III sold 3.5 million copies in the first day and 6.3 million copies in the first week. Another 1.2 million copies were given to subscribers to Blizzard's Annual Pass service. The Diablo III release was the fastest-selling PC game of all time.