A recurring topic, but it comes off the back of this:
http://www.businessinsider.in/Legendary-director-Werner-Herzog-says-he-wants-to-play-a-Bond-villain-I-think-I-would-be-good/articleshow/54797757.cms
Werner Herzog thinks he'd make a good villain. I don't like his chances now after reading he believes the last six or so Bond villains have been "weak". Aside from Silva (and Dominic Greene imo), the others haven't been as good as they should have been, so he does make a point.
But opening this up as a more general conversation. I'd always thought Christoph Waltz would have made a good Bond villain, and that it was only a matter of time before he'd pop up in one of the films (along with Lea Seydoux and Ralph Fiennes, actually - though not as villains - and they both popped up!) but that didn't quite pan out as it should. Here's hoping this list might have a better chance:
Anthony Hopkins - apparently was cast as Augustus Trevelyan (before the character became Alec) and Elliot Carver (when he pulled out because of script changes). He's the master of villainy and should take full advantage of the greatest film series ever.
Stellan Skarsgard - Versatile and with a strong degree of gravitas, he's born to play a Bond villain. I could easily picture him as the unhinged Blofeld in the YOLT novel.
Carice Van Houten - Perhaps getting on to play a Bond girl (maybe Monica Bellucci has since changed that?) but she'd portray a wicked villainess. She has the chops and range - her performance in Black Book was outstanding.
Anjelica Huston - If we need another villain in the mould of Rosa Klebb and Irma Bunt, she could be it. We've had some exceptional American Bond villains in the past (Zorin, Sanchez), so perhaps she could add to that list. This one is a little more left of field, so wouldn't be to disappointed if it doesn't happen - it probably won't - but it could be interesting.
And a Bond villain who should have been: Alan Rickman.