'Dexter': John Lithgow to kill in threes
Like the third season of "Dexter," the fourth will feature a long-term guest star, only instead of Jimmy Smits playing an assistant district attorney, John Lithgow will portray a character planted decidedly on the other side of the law.
According to Showtime's press release, "Lithgow will play Walter Simmons, an unassuming, mild-mannered suburbanite who has been living a dual life as one of America’s most prolific and deadliest serial killers. Dubbed the 'Trinity Killer' because of his proclivity to kill in threes, he relocates to Miami after being tracked by FBI Special Agent Frank Lundy (Keith Carradine). Brought on to assist in the investigation of Miami’s latest serial killer, Dexter Morgan (Michael C. Hall) becomes fascinated with Trinity’s killing methods and his ability to evade capture for almost three decades."
Lithgow will be featured in all 12 episodes of Season 4, which is scheduled to premiere Sunday, Sept. 27, on Showtime.
While Lithgow has acted in as much drama as he has comedy, here's hoping that he's allowed to utilize a bit of his comic experience on "Dexter," which tends to be at its best when it employs gallows humor.
— Claire Zulkey
I was trying to figure out what specifically it was about this season of "Dexter" that failed, by and large, to elicit that sensation of horrified delight that I felt with the first season, and I think it's that the audience saw so little of Dexter the Serial Killer. We rarely saw Dexter (Michael C. Hall) kill someone simply because it was on his list of things to do -- each murder was a part of a much larger storyline. And while I can see the appeal of ideas such as "What would happen of Dexter got married?" "What would happen of Dexter had a friend?" I think back to my days as an "X-Files" fan and remember that I always liked the stand-alone episodes of the show more than the ones that were tied into the bigger plots.
It's official: "Dexter" has turned me into a monster. While I wondered whether the excess gore on tonight's episode, specifically Anton's (David Ramsay) stripped flesh and Ellen Wolf's (Anne Ramsay) cadaver in its various forms (being waved by Harry, being dug up by Dexter (Michael C. Hall) or on the medical examiner's stretcher), was really necessary, I at the same time found that all the ickiness helped contribute to one of the best episodes of the season. 
"Isn't this a bit..." "...morbid?" Dexter conversed with his friend, the terminally ill Camilla (Margo Martindale), in tonight's episode. They were discussing her funeral plans, and I so hoped to see Michael C. Hall in a scene with a funeral director, but a "Dexter" and "Six Feet Under" crossover episode will have to wait.