Reddit reviews Watchmen

Check out Parker: The Hunter - It's a great crime noire tale with very unforgiving anti-hero at it's core. It's a story about love, betrayal and retribution and is fantastic.

http://www.amazon.co.uk/Parker-Hunter-Darwyn-Cooke/dp/1600104932

Also you should check out Saga of The Swamp Thing if you enjoyed V for Vendetta, and Watchmen too. Both are by Alan Moore and while Watchmen has the more violent and anti-hero feel, they both get pretty dark and are written fantastically well.

http://www.amazon.co.uk/Saga-Swamp-Thing-Alan-Moore/dp/0930289226/ref=sr_1_2?s=books&ie=UTF8&qid=1344687793&sr=1-2
http://www.amazon.co.uk/Watchmen-Alan-Moore/dp/1852860243/ref=sr_1_1?s=books&ie=UTF8&qid=1344687811&sr=1-1

One more you might enjoy would be Arkham Asylum - Grant Morrison really goes to town on this one and it's some of his darkest work. I know it's not exactly the anti-hero you were looking for, but it might be the right up your street if you're into the darker books.

http://www.amazon.co.uk/Batman-Arkham-Anniversary-Grant-Morrison/dp/1845760220/ref=sr_1_1?s=books&ie=UTF8&qid=1344687884&sr=1-1

i got them all in one from amazon (in hardback though)

http://www.amazon.co.uk/Watchmen-Alan-Moore/dp/1852860243