Blizzard Entertainment, Inc. is an American video game developer and publisher based in Irvine, California. A subsidiary of Activision Blizzard, the company was founded on February 8, 1991, under the name 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 eventually Blizzard Entertainment after being acquired by distributor Davidson & Associates. Shortly thereafter, 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 expansion for Diablo III, Reaper of Souls; the online collectible card game Hearthstone; the multiplayer online battle arena Heroes of the Storm; the third and final expansion for StarCraft II: Wings of Liberty, Legacy of the Void; the multiplayer first-person hero shooter Overwatch; and the eighth expansion for World of Warcraft, Shadowlands. The games are operated through 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 majority owner Vivendi. As a result, Activision Blizzard became 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.

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