Well, I couldn't get them all, but here's what I could think of:

I actually think Jackie Chan would be an inspired choice for Twoflower. Or else, if you wanted someone younger (though I guess not, since he has a daughter), Masi Oka of the new US show "Heroes" would be brilliant--his character essentially IS Twoflower. :)

Commander Vimes - maybe too sexy, but Daniel Craig?

Captain Carrot - buff him up a bit and I think Ewan McG. could hit this one out of the park.

Corporal Nobby Nobbs - I agree, Andy Serkis would be PERFECT.Lord Vetinari - Much as I adore Alan R., he's not as angular as he used to be. If we had the A.R. of "Robin Hood" perhaps.

Igor - which one? ;)

DEATH - gotta agree with Christopher Lee.

Ponder Stibbons - Michael Sheen? He was so endearing in "Heartlands"...


Granny Weatherwax - if we can count the deceased, I would actually say Katharine Hepburn. Her beauty could be made pretty severe, and she had that no-bullshit air about her. I think she'd be a perfect practitioner of Headology. ;)

Nanny Ogg - I know she's way too young, but for some reason Brenda Blethyn springs to mind. I think it's her portrayal of the super-flooze Mari Hoff in "Little Voice".

Magrat - I was a little disappointed in Jane Horrocks' Mag. in the animated "WS", because I'm a huge fan of hers. But none of the voices in that really made me happy, and I think it may have been the direction rather than the acting.

Tiffany Aching - hmm. For the earlier books, let's see how this Dakota Blue Richards girl turns out (the Golden Compass/HDM films).