John Rawls, an Australian who I'm mostly familiar with as a vampire from 30 Days of Night, just looks creepy, and I think he'll be a good guy to take on all the Myrdraal and Draghkar roles, including Shaidar Haran.
Mickey Sumner seems to sum up the kinda pretty, mostly bitchy look of Darkfriend Mili Skane, aka: Lady Shiaine Avarhin, a minor villain who, like a double-sided coin, always seems to turn up. She's actually probably one of the most oft-appearing villain characters.
I cast Irish actor Anthony Brophy (The Tudors) in the role of Daved Hanlon, mainly because he's as close as I can figure to what "hatchet faced" looks like, plus I like the guy. Not a huge part, though.
For the Golem, who might make a fun recurring villain even if the plot line that introduces him isn't used, I decided it would be more necessary that the actor be a contortionist than that he possess a ton of acting skill. I almost went to the go-to contortionist/actor Doug Jones, but the part is pretty small, so I googled for others and came up with British contortionist Richard Rosson, aka Rubber Ritchie. He'll more than do.
Lord Luc Mantear, and his dreamworld counterpart Isam "Slayer" Mandragoran, are two more parts that require large actors and since both are men of few words, acting talent is secondary to look and height. Spencer Wildling will play Luc, because he's more likely to sound like he belongs in that world, while Robert Maillett will play Slayer.