- Ensemble Dark Horse: Violet Elizabeth Bott is absent from most of the stories (and doesn't get introduced at all till the fifth book in the series) but is almost certainly the best known character other than William himself.
- First Installment Wins: The first book is easily the most popular and the only one most people could name. Many people aren't even aware that there are 38 more after that.
- I Am Not Shazam: In a rather odd tendency, "Just William" is sometimes applied in media to the main character (e.g. "...a classic child hero in the mould of Harry Potter, Charlie Bucket or Just William") as if it were his name. It is, in fact, the perfectly serviceable William Brown.
- Just William is, technically, merely the title of the first book: nearly every title in the series takes the form of either "___ William", "William the ___" or "William and ___". The term is frequently used casually to refer to the series as a whole, though it should really be known simply as the William series.
YMMV / Just William