World of Warcraft (often abbreviated as WoW) is a massively multiplayer online role-playing game (MMORPG) by Blizzard Entertainment. It is the fourth released game set in the fantasy Warcraft universe, which was first introduced by Warcraft: Orcs & Humans in 1994. World of Warcraft takes place within the Warcraft world of Azeroth, approximately four years after the events at the conclusion of Blizzard's previous Warcraft release, Warcraft III: The Frozen Throne. Blizzard Entertainment announced World of Warcraft on September 2, 2001. The game was released on November 23, 2004, on the tenth anniversary of the Warcraft franchise.
- "The Zarnecki Incursion", Sheldon's WoW account is hacked into and his virtual stuff is stolen including a "Battle Ostrich" named Glenn. Penny helped him get this stuff returned after the gang failed in their quest.
- "The Fuzzy Boots Corollary", the gang is playing World of Warcraft and attempts to retrieve the "Sword of Azeroth". Sheldon ninja loots it and abandons the others to sell it on eBay, which is then immediately bought by Howard.
- "The Weekend Vortex", while having a Star Wars gaming weekend, they mention a similar WoW weekend where their neighbors thought they were dead from the smell coming from their apartment.
- "The Hot Troll Deviation", Penny learns that Bernadette broke up with Howard when she found him having cybersex with a troll while playing WoW. The troll turned out to be a male janitor working at CalTech.