Williams is currently writing the Shadowmarch series, the first volume of which was published in November 2004. The second volume, Shadowplay, was published in March 2007. The third volume currently work-titled Shadowrise is currently being written and a fourth and final volume will conclude the series.
In July 2006, Williams started publishing a new six issue comic mini-series called The Next through DC Comics. A second series for DC Comics called The Factory is currently in planning stages. In addition, Tad wrote Aquaman: Sword of Atlantis for DC Comics starting with issue #50, a project which began in March 2007 and ended with issue #57.