In Vietnamese mythology, Lạc Long Quân is the dragon king described as an ancestor of the Vietnamese people.
Lạc Long Quân, whose name means roughly “Dragon Lord of Lạc,” is a legendary ruler in Vietnamese origin traditions. He is portrayed as the son of Kinh Dương Vương and as belonging to a dragon-associated aquatic lineage.
The best-known story says that Lạc Long Quân married Âu Cơ, a mountain fairy or仙-like figure in later descriptions. She gave birth to a sac containing one hundred eggs, from which one hundred children emerged. The couple eventually separated because their natures and homes differed: Lạc Long Quân returned toward the water, while Âu Cơ went to the mountains.
The story explains the phrase “children of the Dragon and the Fairy,” a major expression of Vietnamese national origin. Lạc Long Quân should not be confused with Thủy Tinh, the water spirit who battles Sơn Tinh.