Dexter is a television show on Showtime that's about a bad guy. He knows he's a bad guy, but he's not going to stop.
Dexter Morgan is a serial killer who exclusively kills other serial killers who have escaped justice somehow. But that isn't all he is. He's also a blood spatter analyst for the Miami police. His intimate knowledge of their investigation techniques, as well as detective skills and forensic experience, allows him to both escape being found at (at least, at the beginning of the show) and to hunt down his murdering prey.
You kind of get this weird feeling, somewhere around 4 or 5 episodes in, that you want Dexter to keep killing people. This is a credit to the show. It's not so black and white as you think it is going in, although I'm sure people will come in here now that I've posted that in the OP and say, "I've been rooting for him to get caught since Season 1!" Okay, guy, you don't count.
The show is based on this book
by Jeff Lindsay. Apparently the first book is pretty good, and the show follows it fairly
closely. The second season of the show is more of an adaptation distillation, but totally different from the second book. By the third season, the show has become something else totally apart from the books, and according to people who have read past the first book, this is a very good thing
The show has won numerous awards. The list is too long, so if you want to see, go here
Right now, the show is on Season 8. You can find trailers for it somewhere but don't go find them because all a Dexter trailer does is fake you out.
=-=-=-OFFICIAL THREAD POLICY REGARDING SPOILERS-=-=-=
New viewers be fucking warned!
We do not spoil anything from the prior season until the new season arrives. The DVDs do not come out for each season of Dexter until directly prior to the new season. So right now, you can freely discuss seasons 1-7 in this thread without using spoiler tags. This is a show where ruining something for a new person absolutely destroys the impact. There are many twists and turns and I will personally report anyone who reveals them and ignores this spoiler policy.
So to recap:
Seasons 1-7: Okay to openly discuss.
Season 8: I will fucking cut you.