If you'll notice under my profile, Terry Pratchett is listed amongst my all-time favorite authors. I don't have his books, but my Mum and Dad do, so I just borrow them. My sister has the illustrated version of "The Last Hero" about Cohen the Barbarian and the Silver Horde's last hurrah. As for my favorites, it's a toss-up between the watch, the witches, and the wizards (or wizzard as may be the case) of the Unseen University. Of all the characters, I think my favorites are The Archchancellor, Sam Vimes, Death (and the Death of Rats), and Greebo the Cat.
One thing I always do when reading is try and find an applicable person, or at least their voice, for each role. Here are a few that I've come up with, and what previous roles each did to inspire such thought. Of course, since Discworld is very much British, I can only hope that there are other "Yanks" out there besides me who actually get the humor (I was raised on Monty Python and Blackadder). Just curious to know what you guys think:
Rincewind - Eric Idle (he did the voice in the videogames)
Archchancellor - In my mind, Brian Blessed is about the only person with the voice and half-mad demeanor fitting (picture the Condor King from Flash Gordon, or as Richard IV in Blackadder)
Carrot - Hugh Laurie (at least the voice, anyway)
Nobby - Tony Robinson (think the scabbiest version of Baldrick in Blackadder. He also did the voice of Nobby, as well as Dibbler, in the videogame)
Granny Weatherwax - Sian Phillips (in the same demeanor as Livia from I, Claudius)
Nanny Ogg - Patsy Byrne (Nursey from Blackadder)
Death - I always pictured the voice of Sean Connery, but then saw a cartoon version of Wyrd Sisters, in which Christopher Lee does the voice. Both I think are equally fitting.
Lord Vetinarri - Rowan Atkinson (yes, I'm a big Blackadder fan, if you haven't guessed already!)
Pondor Stibbons - Daniel Radcliff in about five years
Fred Colin - Possibly Robbie Coltrane