1. The Vampire Diaries
Back in the '90s, LJ Smith started writing a 13 book series that Julie Plec and Kevin Williamson adapted into the Vampire Diaries tv series in 2009. The series follows the same characters, but has a wildly different storyline aside from the emphasis on friends and the infamous love triangle between Elena Gilbert and the Salvatore brothers. It's definitely worth the read if you want to dive back into the tvd universe.
2. Sweet Magnolias
There's only one season of Sweet Magnolias on Netflix, but it's actually based off of an 11 book series by Sherryl Woods.
3. Bones
This series kept me going during quarantine, so you can imagine my excitement when I found out it was based off an 18 book series by Kathy Reichs.
4. Normal People
Normal People is a 12 episode mini series based off a novel by Sally Rooney. I'm a huge fan of book to movie/tv adaptations, but I always find myself getting angry when I see changes from the book to the movie. Of course there were little changes, but I think this is the best book to show adaption I've ever seen. Definitely worth the read and the watch.
5. You
This series took the world by storm, but few people know it's based off of a series by Caroline Kepnes. The Netflix series paints a very different, more sympathetic picture of Joe than the books, but both are definitely worth the watch/read. (Book 4 is in the works, so that probably means we'll see a season 4 on Netflix!)
6. Gossip Girl
Sticking with the Penn Badgley theme, Gossip Girl is also based off a 13 book series by Cecily von Ziegesar. I haven't read this series, but from the looks of it, it seems like people like the books better than the series, so if you're looking for more about your favorite characters on the Upper East Side, you should probably check these books out.
7. Pretty Little Liars
If you're anything like me, the Pretty Little Liars tv series ran a little bit too long and so did the books. But, the books are far different than the show, so if you want to explore the lives of these characters more than the series did, these books are probably a good fit for you.
8. Dash and Lily's Book of Dares
This book and this series are ranked high on the list on the list of cute, young adult series. Not too much was changed between the book and the show, and you can never go wrong with a series that features a Jonas Brothers appearance. It's the perfect thing to watch or read to get you in the Christmas spirit.
9. 13 Reasons Why
With the popularity of this Netflix series, it's easy to forget that it's based off of one single book which varied wildly from the book. The book is definitely worth the read and it's interesting to see how much the show changed from the original intention of the author.
Runner Ups:
Friday Night Lights
The Handmaid's Tale
Orange is the New Black
The Haunting of Hill House
Game of Thrones
I didn't watch enough of any of these series to talk about a show/book comparison, but given the popularity of these four shows, I'd say it's worth the time spent watching/reading them.