Interesting question. I don't resemble any celebrity physically or in (perceived) personality. But I did have a friend who reminded me of Susan Sarandon, not so much physically as certain facial expressions. She got the same comment from someone else that same week. I couldn't tell if she was displeased - I knew she wasn't exactly a fan of her politics.
I've been told forever that I look like this girls twin. It started in 3rd grade, when my teacher saw The journey of Natty Gann and she told me I look like her.... over the years friends and family have all told me I look like either Meredith Salenger or Justin Bateman.
I had a woman at work tell me I looked like the bastard child of Tobey Maguire and Bruce Campbell. Should I have been offended? I mentioned it to my sister and she agreed whereas my wife just laughed. OK, now I know I should be offended.