"Contemporary or classic novels, plays, poem and short story anthologies, that any serious reader should read at least once in his or her life." (Goodreads)
This challenge is perhaps a tad less "anglocentric" than the "BBC's 100 Best Books" challenge posted a few hours ago. But it might be interesting to compare this user-voted list vs that from an authoritative source like the BBC.
This is the state of the list in July 2020. Some duplicates have been removed.