There are a lot of good books listed already...but if you like classic books try Alexandre Dumas. His books are great reads. I'd start with The Three Musketeers and The Count of Monte Cristo. If you like those, there are plenty more (The Man in the Iron Mask, etc.).
https://en.wikipedia.org/wiki/Alexandre_Dumas
A couple of my all time favorites, The Red and the Black by Stendhal and The Cossacks by Tolstoy.