I've always heard someone say "oh this is always on the AP exam" or "something about this guy will definitely be asked", some are more obvious than others, but after taking a few practice exams, I realized that's not always true. (about them being obvious)

For example, Machiavelli always is there. ( or so I hear ) and special attention to the Holy wars, or Cessil Rhodes, and especially all the thinkers of the Enlightenment.

Now it's obvious why they're there, they're very important. But questions like "which enlightenment author would support this quote..." or something like that stresses me out.

What other people or events would people who've already taken the exam say are re-occuring or especially important?