Like many writers, I like to picture someone as the hero for my book. Not only does it help me describe him but it keeps me focused. But for me, it's not just important that the character look right, his personality must be a close match to my character's too, otherwise the visual won't work.
For The Witchblade Chronicles books, Honor Bound and Kiss Of Ash, I started with an actor in mind and then found the right image to convey that character's looks AND personality. Sir Nicholas Merritt, the hero in Honor Bound, is boyishly charming. Women love him but he has a deadly serious side that he doesn't let many people see. A young Sean Connery in the James Bond movies had just the right combination of charm and devilry.
The Witch Hunter in Kiss Of Ash is based on Richard Armitage's character in North and South. Dark, mysterious, brooding with a bad reputation.
Sometimes my descriptions deviate from the image at hand but the pictures always help when I get stuck. And it never hurts to glance over an image of these guys once in a while
Pop over to my Other Books thread to see who I based Black Jack Knight from The Adventures of Miss Upton and the Sky Pirate on.