One thing about MacBeth is that Lady Macbeth is a very strong figure behind him. How about a politician, such as Bill Clinton? His wife is very ambitious, as is Bill Clinton's wife Hillary, who has been called a Lady Macbeth in the media before.

Or, perhaps you could say someone like Dick Cheney, who seeks power and will do anything to get it.

For Banquo, you could run with that theme and make him Colin Powell-- someone who went along with an evil plan but perhaps was not the main actor in it.

Hmm. A tough set of comparisons, actually. Do they have to be in the same country/ industry / discipline? It is easier if they don't.

How about Colin Powell and Banquo. Powell was a warrior, loyal in tough situations, and had predictions made about his future position (people said he could be president).

If we assume Macbeth's dominant characteristics are taking power he doesn't deserve, and listening to false predictions that shape his fate, how about Osama? He's following twisted predictions, killing those who don't deserve it, and doesn't seem to believe in his own death. (The problem there, of course, is that there's no Lady Osama/Macbeth.)

Maybe Kim Jong-il is better. There were omens at his birth, and so on.