Bad person - interesting person?

What makes a person interesting?

I don't mean the beauty of a person, because that's in the eye of the beholder, I mean a really, really interesting character. 

To me, the bad person of a movie or series is always the most interesting one. But why?

I guess because we also expect that we'd have such a person in our lives (or is it just me?).

I never met a person who was that interesting that I wanted to find out more about his or her character.

I wish that one day I'll meet that kind of person.

PS. I'm not trying to say that anyone outta here is boring.

Good examples?

Tony Stonem from Skins. 
I'd describe him as a cold, nasty, arrogant and big-headed person. But there's a background, there's a reason why he acts like that. 

 

Blair Waldorf  from Gossip Girl.
Very similar to Tony Stonem, I think.
She's just playing the bad bitch, she tries to hide that she's a broken-hearted girl.

Liam and Noel Gallagher, members of the British band Oasis.
Both had an unhappy childhood, they were often beaten by their alcoholic father. Everyone called Liam "Peggy's shadow", because he was always by his mom's side, while Noel had to feel most of their dad's violence.
To this day the two brothers have a bad relationship, even if they're adults.
They're famous for their bad behavior and nasty demeanor, but if they're really like that, why should they write songs like Wonderwall?
You should read their story on wikipedia, it's very interesting.

Do you know anyone with a really special character?