The first BlizzCon was held October 28–29, 2005. The Major announcement was the first World of Warcraft expansion pack, The Burning Crusade, as well as the new Horde race, the Blood Elves.
Playable demos of The Burning Crusade and StarCraft: Ghost were also available.
In 2006, Blizzard had neither a BlizzCon nor a Worldwide Invitational, instead they attended the Electronics Entertainment Expo (or E3) and unveiled the new Alliance race for the Burning Crusade expansion pack, the Draenei. This was the last E3 Blizzard attended, and they have since preferred to hold their own events.
The only game that had a playable demo was the Burning Crusade, as StarCraft: Ghost had been "indefinatly postponed" by this time.
On the 12th of April 2007 Blizzard announced that they would be holding a second convention this year. This convention was held on August 3, 2007. Details about the event are limited to what was included in the announcement;
Highlights for this year's BlizzCon included:
- Discussion panels with Blizzard game developers;
- Competitive and casual tournaments, including a World of Warcraft TCG tournament;
- Costume, machinima, and character sound-alike contests with great prizes;
- Live orchestral performances of music from Blizzard games;
- And many more exciting activities.
The major announcement at the convention was the second World of Warcraft expansion pack, The Wrath of the Lich King.
During the convention, the Terran race was revealed, along with aspects of the Terran campaign. A lore discussion and art discussion  were held. Those attending the convention also were able to play skirmished StarCraft II matches, either multiplayer or against a computer, using either the Terran or Protoss races.
On May 12, 2008, Blizzard announced their third Blizzcon event gaming convention, to be held at the Anaheim Convention Center in Anaheim, California on October 10 and 11. In response to the demand to accommodate more attendees, this year's event was expanded from two convention halls to three.
Highlights for this year's Blizzcon included
- Hands-on play time with upcoming Blizzard Entertainment releases
- Discussion panels with Blizzard Entertainment developers
- Competitive and casual tournaments for players to showcase their talents
- Areas and activities devoted to licensed products such as the World of Warcraft® Trading Card Game
- Costume, machinima, and character sound-alike contests with great prizes
- Commemorative merchandise based on the Blizzard Entertainment franchises
- A silent auction
The major announcements at the convention were the Wizard class for Diablo III and the intro cinematic for Wrath of the Lich King.
Playable demos of Wrath of the Lich King, Diablo III, featuring the new Wizard class, as well as the already existing Barbarian and Witch Doctor classes, and StarCraft II.
The Monk was also revealed during this event, along with the third World of Warcraft expansion pack, Cataclysm.
Playable demos of StarCraft II, Cataclysm and Diablo III were also available.
On March 25, 2010, Blizzard announced the fifth BlizzCon was going to be held October 22–23, 2010 at the Anaheim Convention center.
- "Malthael, the Angel of Death, grows restless. Having sieged the historic city of Westmarch, he now sets his sights on a new metropolis: Anaheim, California—the great gamer haven of the West. Soon, his forces will begin their march on the hallowed halls of BlizzCon and only you, mighty Nephalem, can defend its denizens and help put a stop to the coming apocalypse."
"Are you ready?"
At BlizzCon 2013, Diablo III players who purchase a virtual ticket unlocked the Take a Look at Banner achievement, which grants players a new Banner Pattern, Banner Sigil, Banner Shape and Banner Accent. Diablo swag includes a Reaper of Souls chain, a Diablo/Skeleton King/Butcher t-shirt, and a Diablo figure in Blizzard's Cute But Deadly range.
- A look at the creation of the Reaper of Souls intro cinematic.
- A Reaper of Souls preview as the development team reveals more about the game's environments, monsters, game modes, features, and more.
- A lore Q&A for Reaper of Souls.
- A gameplay feature, with special focus on the Crusader class.
- An open Q&A about the console and PC versions of Diablo III.
BlizzCon 2014 ran from November 7-8 at the Annaheim Convention Center.
- November 7: A "what's next?" panel for Diablo III, with new features and concepts being discussed (2:15-3:15PM).
- November 7: Community Corner—a chance for players to interact with designers Wyatt Cheng and Travis Day in an open discussion panel (3:30-4:45PM).
- November 8: Evolving Reaper of Souls; includes discussion about upcoming features, and a new Legendary Item will be designed with the community (12:45-1:45PM). The item turned out to be Convention of the Elements, named after the event.
BlizzCon 2015 was the ninth installment of Blizzard Entertainment's annual BlizzCon event. The 2015 BlizzCon took place across November 6-7, 2015, at the Anaheim Convention Center. A pre-BlizzCon charity dinner was held on November 5 in support of the Children's Hospital of Orange County.
BlizzCon 2015 tickets went on sale in two batches on Wednesday, April 15 at 7 p.m. PT and Saturday, April 18 at 10 a.m. PT through the online event ticketing service Eventbrite, priced at $199 each (plus applicable taxes and fees). Virtual tickets went on sale in August, 2015.
The event had over 25,000 attendees and was streamed by over 10 million users.
The event's "goodie bag" included a Diablo keychain. Interviews included the Diablo setting. A dev talk was held from 3:30-4:30 PM on Friday. A replica of the Slaughtered Calf Inn was present where discussions could be held with members of the development team. Those who attended the event or purchased a virtual ticket received a themed pennant, special portrait and Murkgoblin pet (PC/Mac versions only).
BlizzCon 2016 (a.k.a. BlizzCon X) was the tenth BlizzCon event. It was held from November 4-5, 2016.
BlizzCon 2016 tickets went on sale in two batches on Wednesday, April 20 at 7 p.m. PT and Saturday, April 23 at 10 a.m. PT through the online event ticketing service Universe, priced at $199 each (plus applicable taxes and fees). A pre-BlizzCon Benefit Dinner the evening of Thursday, November 3 in support of Children’s Hospital of Orange County (CHOC). Tickets for this event go on sale Wednesday, April 27 at 7 p.m. PT, priced at $750 each, and attendance will be limited.
A virtual ticket could be purchased for the event. In-game bonuses were given to those who purchase these tickets.
The "goodie bag" was sent out ahead of the event to a number of individuals. Not long afterwards, a number of sites reported on an apparent printing error with the dice. Where they should read 1-1-1, they were instead been printed as 1-1-4. It has been suggested that this is a code for the date of the event (the 4th day of the 11th month). Likewise, the insignia on the dice bag was not the Diablo III logo, but rather a four-sided compass with four smaller points, with a "D" located inside a square (a four-sided shape). Media speculated that this was a hint at a supposed "Diablo IV" game. No such game was revealed at the event.
- Friday, November 4, 1:30PM: Darkmoon Faire Quick Talks
- Friday, November 4, 5:00–5:45PM: Diablo 20th Anniversary Panel
- Saturday, November 5, 4:00–5:00PM: Diablo III Dev Talk and Q&A
- Saturday, November 5, 12:30PM: Darkmoon Faire Quick Talks
BlizzCon 2017 was held on November 3-4, 2017, at the Anaheim Convention Center. Tickets went on sale on April 5 and April 8. On October 10, 2017, Blizzard announced that the Murkromancer, a Necromancer-themed Murloc pet, would be rewarded to players who attended the event or purchased a Virtual Ticket.
It was announced Diablo would have a presence at the event, but there would be no announcements for the franchise.
BlizzCon 2018 was held from November 2-3, 2018. The first batch of tickets went on sale on May 9, the second on May 12, and the benefit dinner ticket sale on May 16.
Blizzard confirmed that it would announce some, but not all, of its current Diablo projects at the event. Among the announcements was the mobile game Diablo Immortal that takes place after the events of Diablo II. The announcement of the game was met with unfavorable reactions and backlash.
- Diablo: What's Next—Join the Diablo team as they discuss of what's in store for the heroes of Sanctuary (November 3, 6:30AM—7:15AM)
- Diablo: World and Q&A—Join the Diablo developers as they explore the world of Sanctuary, then stay awhile and listen as the team answers your questions.
- November 3: Blizzard Art Studio: Diablo: Ever want to learn to draw the Blizzard way? Join artists from around the studio as they sketch the dark lord of terror, Diablo, live, and level up your own artistic skills in the process (4:00—4:15AM)
- November 3: Artists at Work: Diablo: Join artists from the Diablo team to see how Sanctuary is brought to life in-game through art, animation, and effects (4:30–5:15AM)
- November 3: The Art of Diablo: Come and learn more from the development team about the art of Sanctuary (10:15—11:00AM)
BlizzConline is a virtual convention to be held on February 19th and 20th 2021, in lieu of the canceled 2020 BlizzCon. The stream will be available for free.
The convention will come with a commemerative 30 Years Blizzard Collection available for purchase. This includes the following Diablo items:
- Epic Pack: Complete set of Diablo III transmog items.
- Heroic Pack: Cosmetic wings
- Essentials Pack: Diablo III pet and portrait
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