Dragons seem to be everywhere. Medieval Europe imagined winged monsters. China developed the lóng, associated with rain, rivers, celestial power, and rulership. Ancient Mesopotamia depicted composite serpent creatures. India preserved traditions of Vṛtra and the nāgas. Biblical texts describe Leviathan. Mesoamerican civilizations developed elaborate Feathered Serpent traditions. Other cultures placed extraordinary serpentine beings in rivers, skies, underworlds, storms, creation stories, royal symbolism, and battles between gods and monsters. Their recurrence creates an irresistible question: why do peoples separated by oceans, languages, religions, and thousands of years repeatedly imagine powerful supernatural serpents and dragon-like beings? The investigation begins with the familiar possibilities—shared prehistoric memory, cultural diffusion, fossils, dangerous reptiles, environmental forces, inherited psychology, and universal archetypes—but gradually discovers that the word "dragon" itself may be obscuring the problem. The evidence does not reveal one universal creature. Instead, it reveals overlapping histories of supernatural serpents, composite monsters, cultural borrowing, independent elaboration, ecological influence, cognitive attraction, and later reinterpretation. The resulting mystery is therefore both smaller and more interesting than the original question. Humanity may not share one ancient dragon. But across many societies, serpents repeatedly became unusually powerful material for the supernatural imagination. Understanding why requires separating genuine historical connections from independent convergence—and determining whether supernatural serpents are actually exceptional at all.