I have linked you to the first of each book in this series or to the complete series as a set. Affiliate links have been used where possible.
Ranger's Apprentice by John Flanagan: Follows young Will and his friends as he learns how to be a Ranger. Fantasy.
Brotherband by John Flanagan: A secondary series to the "Ranger's Apprentice" series. Follows one of Will's friend Hal on his adventures.
Tombquest by Michael Northrup: Similar to the 39 Clues and Spirit Animals (written by several authors). Follows an Egyptian storyline line in modern times.
The Blackwell Pages by K. L. Armstrong: Follows Matt a modern-day descendant of Thor.
Kane Chronicles by Rick Riordan: Written by the popular author of the Percy Jackson series. This one follows two siblings and their interactions with Egyptian gods.
Ascendance Trilogy by Jennifer A. Nielsen: Three book fantasy series.
Five Kingdoms by Brandon Mull:Written by the popular author of "Fablehaven" this one has a fantasy twist in a modern tale.
Fablehaven by Brandon Mull: Two siblings must help run an ancient sanctuary of make-believe beings. Super popular series!
Unwanteds by Lisa McMann: Clever telling of people who have magical powers and those who don't.
Adventurer's Wanted by M. L. Forman: Young adventurers get to pick their own adventures with surprising outcomes and consequences.
The Children of the Lamp by P. B. Kerr: Two siblings discover they are djinn and have special powers and must save the world.
How To Train Your Dragon by Cressida Cowell: The series that inspired the popular movies and TV series. Humorous with funny pictures.
Septimus Heap by Angie Sage: A young boy becomes a magical apprentice and learns his interesting history.
The Menagerie by Tui Sutherland: Similar in style to "Fablehaven" with the escape of magical creatures from a special preserve.
Seven Wonders by Peter Deranges: Similar in style to Percy Jackson in a modern tale of a boy who must use special powers to save the world.
Janitors by Tyler Whitsides: Discover the secret world of Janitors and how they must defend you while you're at school.
The Magic Thief by Sarah Prineas: A young boy is drawn into a world of wizardy and magic.