Dexter (Showtime, 2006-Present) Season 5
Offense: Jordan Chase and his buddies are serial rapists and murderers
The revolving door of showrunners behind Dexter have had one thing in common: By and large, they aren't interested in the moral and ethical and themes one assumes would accompany a series that features a serial killer for a protagonist. From season three onward, each year the show pits its leading monster up against killers far more monstrous than he, amoral creeps so horrible—or so boring (Hey, Colin Hanks!)—that viewers can't help but root for them to end up on his carving table.
What lacks in complexity is usually made up for in entertainment, as evidenced by the revenge-tinged fifth season, which guest stars Julia Stiles. She plays Lumen, a Minnesota native who is welcomed to Florida by way of a serial gang-raping and murdering crew led by self-help guru Jordan Chase (Jonny Lee Miller). When Dexter inadvertently stumbles into one of their hideouts, he frees Lumen and vows to help her track and kill Chase and every other member of his twisted circle.
As previously noted, these are foes that are conveniently too heinous to let breathe, but once the season gets going the avenging is undeniably exciting as they prove themselves worthy adversaries of Dex, although the conclusion is a bit too predictable and neat. Hopefully the impending seventh season will dare to get a little messier.