I seocnd the 39 Clues books. My son, just turned 10, has read the first 2 and I bought him the 3rd for his bday.
The same son, also loves non fiction. On a whim I picked up Who Were The Beatles? He loved it. There are tons of them. Since then he has read, Who was John F Kennedy, Who Was Elvis Presley, Who was King Tut, Who was Leonardo de Vinci, and he is currently reading Who Was Harry Houdini. They are great age appropriate books, full of educaltional info, but the reading is fun. I read along on the Beatles book, and really enjoyed it myself. They even have a Who Was Walt Disney book. The books are by different authors, but they are all the same concept, once you find one you will see the others are written & illustrated the same way.