Blizzard Entertainment, Inc. is an American video game developer and publisher based in Irvine, California. A subsidiary of Activision Blizzard, the company was founded in February 1991 as Silicon & Synapse, Inc. by three graduates of the University of California, Los Angeles: Michael Morhaime, Frank Pearce and Allen Adham. The company originally concentrated on the creation of game ports for other studios' games before beginning development of their own software in 1993, with games like Rock n' Roll Racing and The Lost Vikings. In 1993, the company became Chaos Studios, Inc., and then Blizzard Entertainment soon after being acquired by distributor Davidson & Associates early in the following year. Shortly after, Blizzard released Warcraft: Orcs & Humans.

Since then, Blizzard Entertainment has created several Warcraft sequels, including highly influential massively multiplayer online role-playing game World of Warcraft in 2004, as well as three other multi-million selling video game franchises: Diablo, StarCraft and Overwatch. Their most recent projects include the online collectible card game Hearthstone; the multiplayer online battle arena Heroes of the Storm; the remaster of the original StarCraft and its expansion Brood War, StarCraft: Remastered; the replacement and sequel to the multiplayer first-person hero shooter Overwatch, Overwatch 2; the sequel to Diablo III, Diablo IV; the mobile real-time strategy Warcraft Rumble; and the tenth expansion for World of Warcraft, The War Within. The games operate through Blizzard's online gaming service Battle.net.

On July 9, 2008, Activision merged with Vivendi Games, culminating in the inclusion of the Blizzard brand name in the title of the resulting holding company. On July 25, 2013, Activision Blizzard announced the purchase of 429 million shares from the majority owner Vivendi, which resulted in Activision Blizzard becoming a completely independent company. Since 2018, the company's reputation has suffered from a series of poorly received games, controversies involving players and staff, and allegations of sexual harassment and other misconduct against leading Blizzard employees. In October 2023, Microsoft acquired parent company Activision Blizzard, maintaining that the company will continue to operate as a separate business. While part of the larger Microsoft Gaming division, Blizzard Entertainment retains its function as the publisher of games developed by their studios.

Blizzard Entertainment hosts annual gaming conventions for fans to meet and to promote their games: the first BlizzCon was held in October 2005 at the Anaheim Convention Center in Anaheim, California, which is where all of their conventions have been held since. BlizzCon features game-related announcements, previews of upcoming Blizzard Entertainment games and content, Q&A sessions and panels, costume contests, and playable demos of various Blizzard games. Blizzard WorldWide Invitationals were events similar to BlizzCon held in South Korea and France between 2004 and 2008.