* DamselScrappy: Millie in ''Castle Roogna''.
* GuiltyPleasure: Oh god yes. The puns, the tropes used, the plots... all combined combined with the ParentalBonus makes re-reading the Xanth novels 10-20 years out of the target audience a very guilty pleasure indeed.
** That's if it doesn't produce a "I actually liked reading this? What was I thinking?" reaction.
* MarySue: A fair few, but nowhere as bad as the three princesses introduced later - "Rhythm", "Harmony" and "Melody". Whereas characters previously had a limited talent, which was used in a clever way to solve a plot roadblock, the three princesses have the talent to (described in-text) literally "Do Anything" by using their ~ Summonable ~ instruments. Any inventive solutions to plot roadblocks were thrown out the figurative window, as the princesses (who showcase in most books) will solve the problem by themselves with no intervention by the main character of the story.
** The moons of Ptero also count in a way, as a convenient dumping ground for pun libraries and easy character solutions, due to the presence of "alternate" plot characters and convenient havens for happy, age-inappropriate romances.
* NightmareFuel: What Trent found in Castle Roogna's library in the first book.
* PanderingToTheBase: Xanth is read mostly by hormonal teenagers (of both genders), and Piers Anthony is ''distinctly'' aware of this -- and includes a weird combination of fanservice and strong female characters for both sides.
* PeripheryDemographic: Young kids and teenagers, actually, due to the Puns.
** Funnily enough, Anthony stated in one of his Author's Notes that the reason the Adult Conspiracy was hiding less in later books was that he was offended that his books were being put in the Teens section of the library and wanted to emphasize that the books were meant for adults.
* TheProblemWithLicensedGames: Averted. The AdventureGame based on one of the novels managed to be at least halfway decent.
** Except the novel is based off of the game that is based off the novel. It's maddeningly recursive on YourHeadASplode levels. Basically, in the novel, the protagonists are ''playing the game that is now out, based on the novel'', making it a bit of IWishItWereReal, as well.
*** The Author's Note straightens this out: Anthony wanted to make a Xanth computer game, but lacked the expertise to do it himself. He wrote the novel to show Legend Entertainment what the Xanth game should be like, and they went and made it for him.
* {{Sequelitis}}: And how. The first book was amazingly original, but by Harpy Thyme the prose is so badly written it can be painful to read in places, among other problems. Many people recommend stopping by Question Quest, and giving the later books a miss except those with characters from the early series (like the aforementioned Harpy Thyme, sadly).
** SeasonalRot: There are effectively "seasons" to the books, which can be judged by the protagonists and their connections to the royal family. About the time the series starts wandering further and further afield of Bink's direct descendants, it becomes obvious that Anthony [[MoneyDearBoy is just writing to meet his word count]], with entire chapters of {{Filler}} that either [[BigLippedAlligatorMoment have no effect on the overall story]] or just serve to [[PoorlyDisguisedPilot transparently and hamhandedly introduce characters or situations]] for a [[SequelHook later book]].