DEXTER Season 4 Sneak Peek June 3, 2009 Dexter Watch a sneak peek from DEXTER Season 4 airing this Sunday, December 14, at 9pm on Showtime. This season, John Lithgow has been confirmed to join the cast of Dexter for season 4 as a villain. He will definitely be a great addition to the cast. Read all our Dexter coverage. Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)Click to share on Reddit (Opens in new window)Click to share on Google+ (Opens in new window)Click to share on Tumblr (Opens in new window)Click to share on Pocket (Opens in new window)