MMOs with World Bosses

No queue, no instance, just a massive threat sitting out in the open world — world bosses are the rare fights big enough to pull in dozens of unrelated players at once, turning into a spontaneous, server-wide event rather than a scheduled raid night. Anyone nearby can pile on, loot rolls often go to everyone who contributed, and the spectacle of a giant enemy getting swarmed by a random mob of players is half the appeal. It's group content that doesn't require a group at all. This tag covers MMOs with world boss encounters, from open-world giants that spawn on a timer to massive, server-shaking events built around collective firepower.