Graham McNeill
A writer for the Black Library.
Not Dan Abnett, but forms the Holy Trinity of Black Library writers with him and Sandy Mitchell, (Which makes ADB the Holy Virgin or something)
Wrote the Ultramarines novels and some Iron Warriors shit. When he's writing them, the Ultramarines are not just tolerable but actually awesome.
He's also written several Horus Heresy books, including A Thousand Sons, the first Black Library book to hit the New York Times Bestseller list, the infamous short story The Last Church. On the other hand, he did write The Reflection Crack'd, which had Fabius Bile and friends rape Fulgrim with a pear of anguish. So fail there. Oh, and Codex: Black Templars.
He also wrote the Time of Legend: Sigmar novels, the third novel of which gives a brief preview of the origin story of Morkar the Uniter. Very nice Mr McNeill, now write that story.
McNeill's writing style is very "tell, don't show." His books tend to have characters deliver their lines in uninterrupted chunks with minimal indication of what's going on around them, and very flat emotional inflection in dialogue.
Examples of some of lacking descriptions excerpted from a single page (p. 471) of "Fulgrim," describing the Battle of Istvaan V:
"The pain was unimaginable..."
"The battlefield of Istvaan V was a slaughterhouse of epic proportions."
"...a conflict unparalleled in its bitterness."
On the other hand, his stories have a wealth of background information and detail, and his few character driven stories are very good as well (read Priests of Mars).
Priest of Mars also makes rape camps canon, just thought you would like to know (although they're heretical).
He recently announced that he had been hired as a "senior narrative writer" for League of Legends, and subsequently would not be writing as actively for Black Library as he has in the past. The response to this news on /tg/ was predictable.
Differences with Matt Ward
 | This article or section involves Matthew Ward, Spiritual Liege, who is universally-reviled on /tg/. Because this article or section covers Ward's copious amounts of derp and rage, fans of the 40K series are advised that if they proceed onward, they will see fluff and crunch violation of a level rarely seen. |
He's taller and has less hair than Ward. Also, he wrote the Ultramarines from the perspective of a novelist writer above the third-grade level, so they're not simply Mary Sues. Ward's role as a studio writer meant he had to produce shitty stories to appeal to pre-pubescent boys inability to stop jerking off over the Smurfs leads him to depict them as caricatures of themselves that can do no wrong, whereas McNeill is a more competent writer who's willing to let the Ultramarines have flaws without making them look like absolute failures and didn't have to deal with Head Office's bullshit.
That said he's far from being universally liked. Some Ultramarines fans view him as going too far in the other way. Making them total failures and a vibe of "Cool Smurfs don't follow the Codex" and that the lead character Uriel Ventris, becomes the biggest mary sue of any Smurf. Like many, many other things, this is up for debate.