Blofeld

In Fleming's books itself the incorrigible Blofeld sounds like he'd be a better fit for a Potter novel where he can play some 'creature-who-must-not-be-named' rather than a treacherous villain Bond needs to take care of. He's described as a strange, chameleon-like man who can at one moment be huge and disinterested in sex (as he is in Thunderball) and at another have no earlobes and a syphilitic nose (as seen in You Only Live Twice). 

He's the father of all the other villains and the head of the evil Spectre organisation. He's grossly scarred, utterly deceitful, rich, ruthless and terrifyingly authoritarian. He's also the man who gave birth to Dr. Evil who in turn gave birth to Mini Me. But perhaps the scariest part about him is that he remains undefeated even today. Till date, he remains the only recurring villain in the Bond books and also one of the few to incur more psychological damage to James Bond than any of the others. After all, he is the villain who kills Bond's wife. Donald Pleasance probably did the best job of pulling off this role with the evil, cold and sarcastic vibe that fit perfectly with this character. And then there's that Mao suit. Downright terrifying is all we can say.