The d20 System is a role-playing game system published in 2000 by Wizards of the Coast, originally developed for the 3rd edition of Dungeons & Dragons. The system is named after the 20-sided dice which are central to the core mechanics of many actions in the game.

Wizards of the Coast LLC or Wizards) is an American publisher of games, most of which are based on fantasy and science-fiction themes, and formerly an operator of games retail stores. In 1999, toy manufacturer Hasbro acquired the company and currently operates it as a subsidiary. During a February 2021 reorganization of Hasbro, WotC became the lead part of a new division called "Wizards & Digital".