Not listed in any particular order
1)The Hunger Games by: Suzanne Collins
One of the best series ever, and incredibly popular.
2) The Twilight Saga by: Stephenie Meyer
Another one of my favorites.
3) The Percy Jackson Series by: Rick Riordan
Another great book and also somewhat educational for its Greek origins.
4) The Heroes of Olympus
A continuation of the Percy Jackson series, that also includes Roman myths. This series is not finished; the 4th out of what may be 5 books will come out next October.