Mr. Wallaker
Anyone who has read the book knows that Helen Fielding herself gave what amounts to a casting recommendation for Mr. Wallaker. She describes him as looking like Daniel Craig, and even if she hadn't written that, I would picture Daniel Craig anyway because of the character's actions. I would bet money that Craig's role as Bond influenced her characterization of Wallaker.
Well, looking at the cast list, of course and unfortunately there's no Daniel Craig, so it looks like Chiwetel Ejiofor will be playing Mr. Wallaker. That's still not certain though.
Bridget Jones fans who don't know anything about Mad About the Boy will be in for a rude awakening concerning another character--Mark Darcy. I'll say no more about that. I think it would've provided a bit of box office insurance and an absolute coup if they could've convinced (convinced being the key word) Daniel Craig to do it. He probably would've said no because he seems quite particular about roles and has never appeared in a romantic comedy. The comedic skit he did many years ago with Catherine Tate is proof he'd be good in a rom com role.
There will probably be people saying Daniel Craig is too old for the role anyway. Not so. Bridget herself is in her 50s in Mad About the Boy. Oh what could have been.