Dan Scott
First of all, I don't know why Paul Johansson never won an award for playing Dan Scott.
Secondly, after watching the series again, I think Dan is one of the most complex characters ever; we go from hating him, to feeling sorry for him, to hating him while feeling sorry for him. He did horrible things. Killing Keith being # one on that list, but let's admit, his list of sins is a mile long. But in the end, we see he loves his grandson, Jamie, maybe more than he has ever loved anyone in his life. He turns from this arrogant bastard you want to see suffer, to a broken man, who realizes he had so much in life, and he threw it all away. He hurt his sons. Both women he claimed to love. But at the end, he was sincerely sorry.
The final scene, with him and Keith, after Dan dies, still makes me cry. When he says he's 'sorry for that day and every day that came before' and Keith says he forgives him, and you know they have both found peace. One of the best television moments ever.