Five that come to mind and have acknowledged iconic status in my life:
And here are some which hammered the door of my consciousness as I was about to close this post:
Wuthering Heights by Emily Bronte
Out of the Silent Planet and the Perelandra series by CS Lewis
History of Western philosphy by Bertrand Russell
Tarzan Series by Edgar Rice Burroughs
Chalet School Series by Eleanor Brent-Dyer