Reddit reviews Animation Writing and Development, : From Script Development to Pitch (Focal Press Visual Effects And Animation)

Oh man do I have a list for you!

Joe Murray's Creating Animated Cartoons with Character is an amazing read and he gives some information on the creation process for his shows.

Nancy Beiman's Prepare to Board! talks about story development and character creation, but she mostly covers storyboarding in the book. Beiman also has exercises included as you read, so it feels a bit more interactive.

Jean Ann Wright's Animation Writing and Development covers writing for TV animation. Wright talks mainly about how to land a job as a writer for an ongoing show, but he does cover character in the book.

Bryan Konietzko and Michael DiMartino's Avatar: The Last Airbender (The Art of the Animated Series) talks a bit on character creation for the show and how the show kept evolving until they finally arrived at Avatar: The Last Airbender.

But you shouldn't just stay with finding books on how to create characters for animation. It shouldn't matter if they are animated or not, we need to believe in these characters!

Lajos Egri's The Art of Dramatic Writing
is my personal favorite on character development. Although this book is mainly about writing a play, Egri covers dialogue, characters, character motivation, and story development perfectly. I keep returning to this book everytime an idea pops into my head. I cannot express how much this book has helped me in creating believable characters and conflicts.

Blake Snyder's Save the Cat! is a book I have never gotten around to reading, but I feel it worth mentioning as most of my colleagues and friends keep recommending this book back to me.

And again, although you will learn many new things from these books and they will help you view stories and characters more analytically, you won't get better until you start to create more and more characters and stories. You may also start looking for interviews of your favorite creators and look for what they have to say about character.

Hope this helps!