d20 Modern is a modern fantasy role-playing game system designed by Bill Slavicsek, Jeff Grubb, Rich Redman, and Charles Ryan. The system's core rulebook was published by Wizards of the Coast on November 1, 2002; by 2006, ten additional supplements were released. The game is based on the d20 System and the Dungeons & Dragons 3rd Edition ruleset. It includes various campaign settings along with the tools to build campaigns in modern/contemporary settings.

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.