From Diablo Wiki
The Diablo novels are published books that tell stories set in the Land of Sanctuary. These works were commissioned by Blizzard and written in conjunction with the Blizzard lore and story creators, and they are meant to add additional depth and detail to the fictional Land of Sanctuary.
All of the novels are free-standing and can be read without any knowledge of the game, though their stories will likely be of more interest to fans who want a deeper knowledge of the game world. The Sin War Trilogy was written to reveal much of the early history and mythology of the game world, and it details the wars between the Angels and Demons that led to the creation of humanity.
Additional novels are planned for release after Diablo III, though it's not known if their stories will tie in with the game's plot. The first was revealed in October 2011 with a release date in March 2012, though the title and cover art has not yet been revealed.
These novels are all considered canon, though Demonsbane and Legacy of Blood tell smaller, self-contained stories that do not connect to the larger game plot. The Sin War trilogy develops much of the world lore and backstory of the creation of Sanctuary, plus the eternal struggle between the Burning Hells and High Heavens, and is considered the lore and canon that leads directly into the plot of Diablo III. (With some retcon adjustments here and there.)
- Demonsbane, by Robert B. Marks (2000)
- Legacy of Blood, by Richard A. Knaak (2001)
- The Black Road, by Mel Odom (2002)
- Kingdom of Shadow, by Richard A. Knaak (2002)
- Moon of the Spider, by Richard A. Knaak (2005)
- Diablo: The Sin War: Book One: Birthright, by Richard A. Knaak (2006)
- Diablo: The Sin War: Book Two: Scales of the Serpent, by Richard A. Knaak (2007)
- Diablo: The Sin War: Book Three: The Veiled Prophet, by Richard A. Knaak (2008)
Diablo III Novels:
The Sin War Novels
Unlike the earlier Diablo Novels, which were free-standing pieces not directly connected to the story of any of the games, The Sin War trilogy was written to explain and expand on the history of the land of Sanctuary and the Angels, Demons, and Humans who frequent it. These books were a collaboration between Blizzard's head lore guy Chris Metzen and the novelist Richard Knaak.
- How much of the book is creation of yours, and how involved is Chris Metzen behind the canon storyline of Diablo: The Sin War Trilogy? Do you think the ramifications of this book impact in the storyline of Diablo 3 the game?
- Knaak: This is a pure collaboration between myself and Chris Metzen/Blizzard. All that is written is passed by him and the others there. This will be canon and has adjusted earlier info.
One issue of a stand-alone Diablo comic was published in 2001. The stories were not connected to the larger game plot, instead serving to flesh out the world of Sanctuary in non-essential fashion.
- Tales of Sanctuary (2001)
Diablo 3 Plot
How tightly the story developments in the various novels will tie into the plot of Diablo 3 is not yet known, but they are part of the same storyline. The events in the recent series of books (The Sin War Trilogy) took place thousands of years before the "current" events of Diablo 3, so the connection isn't direct. It likely will be for future Diablo Novels, though. Leonard Boyarsky spoke on this in an October 2009 interview. 
- Hellforge:Speaking of background lore and all that, to what extent will the books from Richard Knaak's Sin War Trilogy be a part Diablo III's storyline/setting. I mean, are you guys taking anything from it at all?
- Leonard Boyarsky: Well, nothing specific. It happened 3,000 years before the events of the Diablo games, but it is... it was our attempt to really kind of get out there – you know, with some of the history of the world and kind of codify the lore to a certain degree. It's been awhile since I read them. I've actually read all of them, and I helped during the process of them.
- Chris Metzen worked closely with him to make sure that his vision for what the Sin War was all about was really put forward there so the history is – maybe some of the particulars might not be exactly the way they end up being presented, but as far as the overall details and the overall thrust of the story, that's lore... our core lore, I guess. And we're – I don't know if we'll refer to them specifically, but that's definitely like background into what we're doing if that makes any sense.
What is Canon?
The D3 TEam has disowned plot and world events from some of the early Diablo products, and done fairly extensive retconing to even the plot developments of the earlier games themselves. This was necessary since the world story, as presented in Diablo I (and to a lesser extent in Diablo II) was largely invented as the game was being made. The creators didn't give a lot of thought to the larger world fiction, carried over a lot of real world material (the heavy Christian influence on Sanctuary's art and decoration), and didn't plan out the story very far ahead.
This drove the fiction into some dead ends, which had to be expanded upon greatly in the Sin War novel trilogy, and created some issues for the further expansion of the world story and plot in Diablo III and its planned sequels and external story properties. (More Diablo novels are planned, and likely other forms of media as seen in the Starcraft and Warcraft univeses; comics, manga, trading card games, and more?)
Plus, it isn't the same class. We aren't taking an old class and updating it. The monk from Hellfire, and in fact the story and content of Hellfire, doesn't exist as far as game lore and story is concerned going into Diablo III.They happen to share a name, the same as all of the other monk classes that have existed in all other RPG's since the beginning of time. It doesn't mean they're related kit/story/flavor wise.
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Abd al-Hazir (Writings)
|Diablo novels||The Sin War Trilogy||Diablo III novels||Diablo comics||Other books|
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