I see science fiction and fantasy in some of these lists. Get a grip.
My stab at the impossible:
Underworld - Don Delillo
Money - Martin Amis
A Confederacy of Dunces - John Kennedy Toole
New York Trilogy - Paul Auster
Catch 22 - Joseph Heller
American Psycho - Bret Easton Ellis
The Death of Ivan Ilyich - Leo Tolstoy
The Remains of the Day - Kazuo Ishiguro
The Naked and The Dead - Norman Mailer
Portnoy's Complaint - Philip Roth
While the following are incontrovertibly superb:
Hmmm. Tricky
Midnight's Children - Salman Rushdie
A Clockwork Orange - Anthony Burgess
London Fields- Martin Amis
The Metamorphosis- Franz Kafka
1984- George Orwell
Animal Farm- George Orwell
To Kill A Mockingbird - Harper Lee
The Catcher in the Rye J.D. Salinger
One Flew Over the Cuckoo's Nest - Kesey Keller
From What I've read so far in my 19 years, in no particular order:
Of Mice and Men - John Steinbeck