Hello.
Since you're asking for a candidate for the Doctor I thought I'd give it a shot.
http://soundcloud.com/jukettaja/doctor-andrey-muggliev1
The first one is a bit snivelly and has that creepy air of one who sees humour where there should be none. I had in my mind Karras, the villain from Thief 2, who despite sounding quite ridiculous managed, through his own demented obsession, to nearly kill everyone in the name of "The Cause" (The Builder, in his case).
http://soundcloud.com/jukettaja/doctor-andrey-muggliev2
The second one is a more somber and darker depiction of the Doctor if a tad less insane. Since you mentioned he ought to be sinister I thought I'd try this approach. It's more akin to my own voice obviously and easier to pull off. It also gives the Doctor a more dignified demeanor.