The three primary designers behind the d20 System were Jonathan Tweet, Monte Cook and Skip Williams; many others contributed, most notably Richard Baker and Wizards of the Coast then-president Peter Adkison.
Cook, Jonathan Tweet, and Skip Williams all contributed to the 3rd edition Players Handbook, Dungeon Master's Guide, and Monster Manual, and then each designer wrote one of the books based on those contributions.
Monte Cook, Jonathan Tweet, and Skip Williams all contributed to the 3rd edition Players Handbook, Dungeon Master's Guide, and Monster Manual, and then each designer wrote one of the books based on those contributions.
John Williams | Robin Williams | Robbie Williams | Tennessee Williams | Williams College | Ralph Vaughan Williams | Ted Williams | Vanessa L. Williams | William Carlos Williams | Hank Williams, Jr. | Hank Williams | Don Williams | Williams | Shirley Williams | Lucinda Williams | Andy Williams | Victoria Williams | Serena Williams | Brian Williams | Vanessa Williams | Esther Williams | Paul Williams | Bert Williams | Rowan Williams | Hype Williams | Wendy O. Williams | Michael K. Williams | John Williams (composer) | Clough Williams-Ellis | Williams-Sonoma |