Gary Gygax Day is observed worldwide every July 27, celebrating the birthday of Gary Gygax, the co-creator of the influential tabletop role-playing game Dungeons & Dragons (D&D). Gygax, born in 1938, developed an appreciation for fantasy and gaming during his childhood and co-founded the International Federation of Wargaming in 1967. He created the medieval miniature wargame Chainmail in 1971, which laid the groundwork for D&D, published in 1974. The game allowed players to create their own characters and embark on adventures, marking the beginning of the modern role-playing game industry. In 2008, following Gygax's death, fans designated his birthday as Gary Gygax Day to honor his contributions to gaming. Celebrations often include playing Dungeons & Dragons, purchasing D&D merchandise, and sharing the holiday on social media with the hashtag #GaryGygaxDay. In 2023, his birthday was officially recognized as Gary Gygax Day in his hometown of Lake Geneva, Wisconsin.