In 2009, Frewer portrayed the retired villain Moloch the Mystic in Watchmen and appeared as the White Knight in the December 2009 Syfy two-part miniseries Alice, based upon Alice's Adventures in Wonderland. He starred as Pestilence in two episodes of Season 5 of Supernatural. He has appeared in several adaptations of Stephen King stories, such as The Stand, Quicksilver Highway, Riding the Bullet, Desperation and Bag of Bones.