Did Michael Buckley write an eighth book to the Sisters Grimm series?

Michael Buckley did not write an eighth book in the Sisters Grimm series. The series officially ended with the seventh book, "The Fairy-Tale Detectives."

However, there are a few things to keep in mind:

* Spin-offs: Buckley wrote a few spin-off books and short stories set in the Sisters Grimm universe, like "The Story Thieves" series and the "The Sisters Grimm: The Mirror, Mirror" novella.

* Fan Fiction: There might be fan-written stories or continuations of the Sisters Grimm series available online, but these are not official works by Michael Buckley.

So, while there is no official eighth book, there are ways to explore the world of the Sisters Grimm beyond the original series.