I myself have killed him on four different characters, and three of them were good guys.
I think the most creative way in which I killed him was when he was on the top floor of Dragonreach. I shot him in the knee (DON'T SAY ANYTHING) and before he could turn to confront me, I used Whirlwind Sprint to move quickly behind him, and stabbed him in the back. He then fell forward, off of the balcony and landed on the table below. To make it that much sweeter, it was the same spot from which he had earlier said to me: "Do you get to the Cloud District very often? Oh what am I saying, of course you don't."