My kids absolutely loved the Eragon, Inheritance books. Also try Inkheart and Inkspell. You can never go wrong with The Hobbit and Lord of the Rings books either. Did he already read the Harry Potter books? There is a reason they have sold millions. The story is incredible!
My son got hooked on reading after trying Obert Skye's Leventhumps series. He has also devoured the Artemis Fowl books. My daughter's favorites are the Fablehavens and Inkheart, Inkspell books. Next up: the Redwall series.
Grand dad, My 11 year old is also a reluctant reader - he is especially hard to get started on a book. However, he also has flown through the Percy Jackson series. (the next book in this series comes out May 6) A librarian suggested "the Extraordinary Adventures of Ordinary Boy - Book 1 - the Hero revealed" and also "The Extraordinary Adventures of Ordinary Boy - Book 2 - the return of Meteor Boy?". My son devoured these two books, giggling throughout. I noticed book 3 is available for pre-order. I also suggest Richard Peck's books "A long way from Chicago" and "A year down yonder" My nephew had to read these when he was in 6th grade and he is also a reluctant reader. My 80 year old dad started reading "A long way from Chicago" along with my nephew to encourage him, and before we knew it, they were fighting over the book. It's really good!
My just-turned-12 son is a voracious reader of series books who is also hooked on the Olympians series. He STRONGLY recommends the Pendragon series for anyone who likes Percy Jackson. He also recommends the Underland Chronicles (Gregor the Overlander is book 1) which are, according to him, not really in the same vein as these others but are good books. He thinks the Lord of the Rings stories are GREAT movies but might not appeal in book form to someone who doesn't love reading because of their "old-fashioned" language. He did enjoy the Leven Thumps books.
I'm a middle school librarian who's seen kids go nuts over Percy Jackson. Those same kids read all of Suzanne Collins' Gregor the Overlander books, and are raving over Skullduggery Pleasant (new one just came out, second in the series). Some of them really like the Ranger's Apprentice series. You could also try Garth Nix's days of the week series (can't remember--brain freeze) starting with Mr. Monday.
My grandson liked The Five Ancestors series (Monkey, Eagle, Tiger, Snake and Crane) by Jeff Stone. He also liked the Shredderman series last year. He likes Percy Jackson more than any other book in memory (doesn't put it down until he is finished) He did not like Harry Potter or Artemis Fowl etc. Garth Nix's series Keys to the Kingdom (begins with Mr. Monday and goes through Saturday) was of interest to him.
He likes books with *real* boys who take action and the more the better. He just turned 11. He finds most of the fiction assigned in school too "emotional" and uninteresting. (He is an "A" student and loves sports.) Riorden has to increase his production for these boys!
If you read the Percy Jackson's books yourself, and then pick up any of the other books suggested you will be able to determine in 20 pages if your grandson will find it interesting.
The Invention of Hugo Cabret by Brian Selznick. He'll love it.
My dyslexic daughter also loves the Molly Moon series by Georgia Byng, although the main character is a girl, so I don't know if that might put your grandson off. It's a fantastic tale about a young girl in a miserable orphanage who discovers she is a world class hypnotist. Eventually, her powers let her freeze and even travel through time. Her best friend is a boy, her dog features heavily, and it isn't even remotely a "girly" book. It's extremely exciting, fast paced and funny, just a wonderful series. Try reading the first two chapters of the first book to him: Molly Moon's Incredible Book of Hypnotism. He probably won't be able to put it down after that.
The Goosebump books tend to be popular with reluctant readers too. David Lubar also writes horror short stories that are sure to delight pre-adolescents, particularly boys.
My little brother who is also 11 loved Susan Cooper's Dark is Rising series, they start with "Over Sea, Under Stone" there are five books in the series. The Chronicles of Narnia are very good and also very relevent with the movies out recently
I just went to a workshop on Boys and Books. The speaker suggested the new graphic novels that are out. They look like comic books, but have good content. They have the old timer stories, such as The Hardy Boys and Nancy Drew in graphic form, as well as biographies. They also have series books. One of the series that is popular is the Bone series by Jeff Smith. She also suggested books with lists, such as the Guinness Book of Records, The Worlds Top Ten... She has a good point when she says, you don't have to read a novel to read. She also suggested many of the books already mentioned.
Terrific post by C.C. Wright. The Bone series is a big hit with all three of my grandsons. I bought a Hardy Boys set but they found them too *old timey*. They love Guinness Books and similar books. Calvin and Hobbes is also a big hit. Right now my 11 year old is reading a book on *The Alexandra Library* (thanks to *Percy Jackson*)
There are some great suggestions here! Also, I have noticed that boys hooked on Percy Jackson easily get hooked on the Warriors series by Erin Hunter and the Guardians of Ga'Hoole series by Kathryn Lasky. These series are wonderful for reluctant readers, since they are full of action.
Also, after finishing the Percy Jackson series, my son read Michael Ford's The Fire of Ares, and loved it. The book is about a young boy in ancient Sparta who goes to Spartan warrior school. Historically very accurate, but a little heavy on the blood and gore for my taste. Boys adore it, though.
People have enjoyed Paolini's Inheritance series (Eragon, Eldest, and two forthcoming books that have more consonants than vowels, and whose titles are just silly). I would say that if you want your grandson to learn that plagiarism is acceptable, then Paolini is your man. Most people think that plagiarism is a bad thing, though (and it is), and so I would concur with almost every recommendation here with Paolini's exception.
And yes, for those that want to argue about it, the first two books qualify for plagiarism. If the Tolkien Estate and George Lucas weren't so filthy rich, and if it didn't look poorly for filthy rich people/organizations to sue a child (although he's well into his 20s now), they would, and for all he's worth. However, the only publicity that suing Paolini would bring to the aforementioned parties is bad publicity. Regardless of the crime, it's never looked upon well in our country if people/organizations that have a net worth in excess of several hundred million dollars sue kids.
I guarantee it: if Paolini was an adult, there would be lawsuits. The plot is Star Wars, the world (down to minuscule traits of different races that are absolutely specific to Tolkien) is 100% Middle-earth.