I struggled a bit with this topic from Long and Short Reviews, because I don't tend to think about redeeming villains. I suppose there was Draco Malfoy of the "Harry Potter" series, but from what I read he was mostly redeemed already by the end of the story.
So the only one I could think of initially was Heathcliff. I love "Wuthering Heights" and Heathcliff's doomed love for Cathy drives the story even as he ruins the lives of everyone else around him. I've read the Clandestine Classic version which shows him living an eternal life in Cathy's arms and definitely found that to be a great ending.
I did, however, come up with one of my own - Reed James.
In my shorts "I Heard Your Voice" and "Tamar Rising" Reed is very much the antagonist - I've had readers tell me they want to slap him. A celebrity medium who secretly uses the sensitives around him to leech their psychic powers, he is an arrogant jerk and I very much enjoyed making him suffer. So I thought when writing the third part of the trilogy, "Spiritwalker", I would try to redeem him.
Sadly for anyone who will read this later this year, I failed. Reed is basically irredeemable.
I did, however, manage to make him suffer a bit more.
So which villain would you like to redeem?