The first and only thing I could think of for the letter X was the Xanth series by Piers Anthony. I don’t know if I would consider them YA, but I think I read them in late elementary school because I found the books at the junior high where I had Chinese school on Saturdays. They were probably a little mature for me, but I enjoyed the humor and the fantasy elements. There was also an older girl at church who collected the series, so she let me borrow a bunch of the books in the series after she found out that I liked them.
Considering how much I read them at the time, it’s kind of sad that I can barely remember anything about them. Looking at my bookshelf, I actually own quite a few of his books, but I couldn’t remember which ones were part of the Xanth series and which ones were part of a different series. I remember now that I liked the puzzles in the Adept series, so I bought books from that series, but I didn’t realize that I only bought the second half (I think). I did manage to find an X book under “Anthony, Piers” on my shelf, though–Xone of Contention, which is part of the Xanth series.
Even with the help of Wikipedia, I couldn’t remember much about the book or the series, so that’s all for this very short post… Only two more to go!
This post is my Blogging from A to Z entry for the letter X.