I'd recommend 'The Sandman' series. It combines fantasy, mythology, and human drama in a really unique way. The art and writing are both top-notch. Also, 'Batman: The Dark Knight Returns' is a classic that offers a darker and more mature take on the Caped Crusader.
Definitely check out Batman: Year One. It provides essential backstory and sets the tone for many modern Batman tales. Also, Batman: Hush is highly recommended for its complex plot and amazing art.
One of the must - read Batman comic book novels is 'The Dark Knight Returns'. It presents a darker and more complex view of Batman in a future Gotham. Another great one is 'Batman: Year One' which delves into Batman's origin story in a very detailed and engaging way. And 'Arkham Asylum: A Serious House on Serious Earth' is also highly recommended as it offers a unique and somewhat psychological exploration of the Batman universe.
Some of the must-read comic book events include 'Crisis on Infinite Earths' and 'Secret Wars'. They have had a significant impact on the comic book landscape.
You should check out the 'The Dark Knight Returns' run. It's a classic that had a huge impact on Batman stories. The art and writing are both top-notch.