Fantasy novels are favorites of many young readers. Here's a look at a couple of good choices:

Since 2003, author Garth Nix has been holding young readers under his sway with a fantasy series called "The Keys to the Kingdom." In the books, Nix offers a hugely detailed, complex fantasy world in which the mystical number seven looms large, from the days of the week in the book titles -- and the characters for which they are named -- to the seven deadly sins. This is fascinating stuff, perfect for true fantasy fans.

Nix's hero is a 12-year-old human named Arthur Penhaligon, whose main concern in the first book, "Mister Monday," is trying to get comfortable as a new student in the local middle school. One day, Arthur has a major asthma attack while running during gym class; he's close to death when he sees a vision of a man in a wheelchair giving him a key shaped like the minute hand of a clock.

The key saves Arthur's life and it sets him on a series of increasingly wild and dangerous adventures as he is named Heir to the Kingdom. Arthur's story continues in "Grim Tuesday," "Drowned Wednesday," "Sir Thursday," "Lady Friday" (all Scholastic, $6.99 each) and the just-published "Superior Saturday" (Scholastic, $17.99). Each book features a different adversary whom Arthur must challenge as he battles to become the rightful Heir.

These adversaries, from Mister Monday through Superior Saturday, are actually Trustees of the Architect, who created everything. The Architect left the Will to govern in her absence, but the Trustees -- each afflicted by one of the seven deadly sins -- have broken up the Will into seven pieces. It is these pieces that Arthur must collect by defeating each Trustee and then taking each of their Keys to finally claim the Kingdom.

Nix's series has developed a deservedly loyal following that has impatiently awaited each installment. These are books that can easily take repeated readings -- there's so much detail in each one that it's hard to take in all at once. For better or for worse, however, it's not a series that can be read out of order; instead, readers need to take the time to wade through each volume to understand what's going on. As a result, anyone who wants to read "Superior Saturday," the latest book, would be well advised to first read the other books.

"Superior Saturday" isn't the best book in the series. It feels a bit too pat and too quickly written. Still, Arthur remains a likable hero whose difficult quest has high appeal for fantasy readers. We'll only know how -- or if -- he succeeds whenever Nix publishes the final series volume, "Lord Sunday." It can't be a minute too soon for Nix's fans. (All books ages 9-14.)

Princess Benevolence lives a storybook life until the tragic deaths of her doting parents at the hands of assassins. Suddenly, Princess Ben, as she is known, is plunged into what she considers a terrible existence as the ward of her cold and exacting aunt, Queen Sophia, whose husband, King Ferdinand, also was killed by the assassins.

The childless Sophia has long disapproved of the casual way that Princess Ben was being raised by her parents and sets out to remake her plump, rather spoiled niece into a fashionable young woman. Princess Ben, however, strenuously resists her aunt's efforts to marry her off to some "specimen of imbecilic manhood" and ends up locked in a tower room, starved of food and affection. It is here that Princess Ben discovers her magical powers, which eventually allow her to help save her country from the enemy kingdom of Drachensbett.

In "Princess Ben" (Houghton Mifflin, $16), author Catherine Murdock presents readers with a wonderfully rich twist on fairy tales, starring a rebel princess who must learn a bit of self-discipline as she works to save her kingdom -- and herself -- from the enemy. Readers will readily identify with Ben's rebellion against her cruel aunt and cheer her refusal to be forcibly transformed into a well-mannered young lady.

Murdock, who zoomed onto the young-adult-literature scene a couple of years ago with "Dairy Queen," has crafted another deeply satisfying portrait of a teenager who must discover her true self before taking on the world. Murdock's decision to have the story told as if Ben is looking back years later brings depth to the tale, while her first-person, formally phrased narration is filled with humor. "Princess Ben" is sure to become a classic among the fractured fairy tales that have become popular in recent years. (Ages 12 and up.)