I’ve been a huge fan of long-running book series for years, and the 45-book series you’re referring to is undoubtedly 'The Horus Heresy' by Black Library, with contributions from multiple authors. The series is a massive collaboration, featuring talents like Dan Abnett, Graham McNeill, and Aaron Dembski-Bowden, among others. It’s a cornerstone of Warhammer 40K lore, blending sci-fi and epic fantasy in a way that’s utterly addictive. The sheer scale of the world-building is breathtaking, and each author brings their own flavor to the overarching narrative. If you’re into grimdark settings with deep character arcs, this series is a goldmine.
What makes 'The Horus Heresy' stand out is how it explores the fall of a galactic empire through countless perspectives. The collaborative effort ensures the story never feels stale, and the lore is rich enough to keep you hooked for all 45 books. It’s a testament to how shared universes can thrive when handled by passionate writers.