There are many great book series for 8 year olds. A few popular ones include:
-The Harry Potter series by J.K. Rowling
-The Percy Jackson series by Rick Riordan
-The Chronicles of Narnia by C.S. Lewis
-The Warrior Cats series by Erin Hunter
All of these series are filled with adventure, magic, and excitement, which are sure to capture any 8 year old's attention. In addition, they are all well-written and offer great life lessons.