How many books are there in the Tarzan series?

The number of books in the Tarzan series is a bit tricky, as it depends on how you define "Tarzan book."

Here's a breakdown:

* Edgar Rice Burroughs' original Tarzan novels: There are 24 novels written by Edgar Rice Burroughs himself.

* Officially authorized sequels: Several authors have written authorized sequels to Burroughs' work. These vary in quality and are considered part of the "Tarzan canon." Including these, the total number of Tarzan books would be higher, but there's no definitive agreement on how many.

* Unauthorized works: There have been many unauthorized Tarzan books written over the years. These are not considered canon, but they exist.

So, the answer depends on what you're looking for:

* Officially published books by Edgar Rice Burroughs: 24

* Including authorized sequels: More than 24, but the exact number is unclear.

It's also worth noting that there have been many Tarzan stories written in other mediums, like comic books, movies, and TV shows, which are not considered books.