Deadwood: This is one of my top three shows of all time, along with Breaking Bad and Doctor Who. Based on historical events and figures, but what it does with them is just unexpected and beautiful. It also has one of the best narrative shifts where they realize that the hero is boring and the villain is awesome, so let's just make the villain the hero in season 2. The best thing about it is that it has more swearing than any show that is not called The Thick Of It, mostly cocksucker (there is one character who only knows three words in English and one of them is cocksucker), but all of the dialogue is in iambic pentameter. It's utter genius.