The union catalogue WorldCat has listed the 100 novels which are found in the most libraries.

Of these the top 10 are:

1. Don Quixote by Miguel de Cervantes
2. Alice’s Adventures in Wonderland by Lewis Carroll
3. The Adventures of Huckleberry Finn by Mark Twain
4. The Adventures of Tom Sawyer by Mark Twain
5. Treasure Island by Robert Louis Stevenson
6. Pride and Prejudice by Jane Austen
7. Wuthering Heights by Emily Brontë
8. Jane Eyre by Charlotte Brontë
9. Moby Dick by Herman Melville
10. The Scarlet Letter by Nathaniel Hawthorne

The complete list is here.