Dungeons & Dragons (D&D) is a tabletop role-playing game (RPG) first published in 1974 by Gary Gygax and Dave Arneson, under the company Tactical Studies Rules (TSR). It was the first game of its kind, pioneering the RPG genre by combining storytelling, character creation, and dice-based mechanics. The game established core elements like the use of dice for determining outcomes, character sheets, and the role of a Dungeon Master (DM) guiding players through adventures. Throughout the 1970s and 1980s, D&D surged in popularity, inspiring other fantasy RPGs like Tunnels & Trolls and RuneQuest. TSR eventually faced financial issues, leading to Wizards of the Coast (a subsidiary of Hasbro) acquiring it in 1997, which revitalized the brand with new editions and expanded media presence.

The success of D&D sparked a vast array of spin-offs, including novels, comic books, video games, an animated TV series, and even a live-action film series. Notable game systems inspired by D&D include Call of Cthulhu and Vampire: The Masquerade. In recent years, the game's popularity was further boosted by actual play web series like Critical Role and Dimension 20, drawing millions of viewers on platforms like YouTube and Twitch. D&D's influence extends to a wide range of merchandise, including toys, miniatures, collectibles, dice sets, apparel, and gifts that cater to both new fans and longtime enthusiasts, making it a cornerstone of modern geek culture.