Here are some of the so say important films I've not seen.
Saving Private Ryan (the plot sounds so stupid which put me off)
Schindler's List (subject too grim, I really can't watch this kind of thing, whoever well done and important the subject is, and we must never forget)
Any Marx Brothers films. Whilst I do find the wise-cracking comedy a bit grating, I really should check out one or two of the classics eg "night at the opera"
Ben Hur - just never got round to seeing it.
Gone with the wind - ditto, that said from the bits I've seem, not sure it floats my boat but am aware I ought to see it.
Magnificent Ambersons - definitely on my list, having seen, and been very impressed by Citizen Kane and Touch of Evil
Never seen Birth of a
Nation, nor for that mater, Triumph of the Will. Both are regarded as cinematic masterpieces, though glorify the KKK / racial segregation, and the Nazis respectively