The Emmy-nominated “Dexter” returns Sunday night for its sixth season, once again dripping with blood and irony as winsome, charismatic, how-are-you-so-perfect Dexter Morgan (Michael C. Hall) both solves and commits murders in Miami.

Showtime’s dark comedy “Nurse Jackie” returns tonight, bringing with it laughs, tension and a handful of pills. Edie Falco stars as nurse Jackie Peyton, an emergency room nurse who doesn’t always follow what she recommends. She pops pills, has an affair and nurses her own way. Jackie doesn’t like to follow the rules of nursing, but she doesn’t care, and neither do we.

Do you remember the last episode of “Weeds?” It aired Nov. 19, 2007, on Showtime.

Imagine that your friendly next-door neighbor is a nice, quiet man who works in the police department, has a wife and kids…and also happens to be a serial killer? Although it’s frightening to believe such things are possible, this is the premise of the extremely popular Showtime series “Dexter.”