A UK perspective, in no particular order in terms of which years we read them (and these are by no means all the books we read, just those that I remember) :
Charles Dickens: Bleak House, Tale of Two Cities, Nicholas Nickleby, Oliver Twist, Christmas Carol
Jane Austen: Pride and Prejudice
Shakespeare: Midsummer Night's Dream, Hamlet, Macbeth, Measure for Measure
Ray Bradbury: Farenheit 451
George Orwell: Animal Farm, 1984
Aldous Huxley: Brave New world
Tom Stoppard: Rosencrantz & Guildernstern Are Dead
Jill Paton Walsh: Fireweed (which I only remember as it was the book we were reading when our English teacher introduced the class to the concept of quantum physics.)
Whether all of thse are "must-reads" is another matter entirely...