Christina Ricci or nobody (maybe Ellen Page because she's just an awesome actress *O* -SHBAAAFF-)
Maybe Christina's name don't remind you anything... Just have a look at this picture, I'm sure you'll recognize her ^^^
Yeah, Christina Ricci is Wednesday Addams ^^^ she also played in Casper, Sleepy Hollow, The Man Who Cried, Prozac Nation, Monster, Black Snake Moan...
and I love her x) To my opinion she would be perfect, but yeah, I can't really have an objective opinion about her, she's one of my favorite actresses ^^^'
But the problem here would be her too pale skin =/ I would well suggest Halle Berry if didn't hate her so much