What was the first book 'series,' using the same characters, and who was the author?

Sorry, but could you explain your question better. I'm a bit thick. LOL sorry again!

Okay, what was the first book with a 'sequel,' that had a continuous story using the same characters?

Lord of the rings. I'm guessing ( ithink) you're not allowed to guess. Ooh i could be right though!

The earliest one I can think of would be the Sherlock Holmes stories, which were written by Sir Arthur Conan Doyle. They started coming out in the 1880's I believe. Although those were first published in magazines, so that might not count.

Another very early series would be L. Frank Baum's Oz books, the first of which came out in 1900. Although most people only know "The Wizard of Oz," Baum wrote something like 20 others books set in Oz, many of which feature Dorothy and the characters from the first book.

I hope this helps.
~The Nimir Ra

Not that they qualify as a series, but Honoré de Balzac (May 20, 1799 – August 18, 1850) is well known for his use of recurring characters in his "La Comédie humaine."

http://www.biblio.com/books/1732911.html

The story of Figaro, the Barber of Seville, makes for several opera libretti. But really the Rossini opera is a prequel to Mozart's "The Marriage of Figaro" (by the librettist Lorenzo da Ponte).

The first seven or eight books of the Bible can be seen as one long book series, but nobody knows the name of the author.

Alexandre Dumas's D'Artagnan / Musketeers series started in 1844 - The Three Musketeers, Twenty Years After, The Vicomte de Bragelonne (also confusingly called Ten Years later). There are other divisions of these books into four volumes, just to make life difficult. The four main characters recur throughout.

Chaucer's Canterbury Tales was writting in the late 1300s. I doubt that this was the first however.

The Tales are a collection of stories, some in verse some in prose, forming a single work and published together.

Here's a possibility: in the 16th century, Rabelais published his adventures of Gargantua and Pantagruel in five books beginning in 1532. The last appeared posthumously in 1564:

https://en.wikipedia.org/wiki/Gargantua_and_Pantagruel