Matthew Farrer

A seriously underrated author for Black Library, mostly relegated to more obscure stuff and hasn't done a novel length work for them for a while. He did the Shira Calpurnia novels making it one of the only novels with the Adeptus Arbites as the main characters, and are pretty good reads at that; the first, Crossfire, probably being the best of the bunch, a detective procedural/thriller against the backdrop of the grim darkness of the 41st millenium. The last of the trilogy, Blind also provides a rare glimpse into the details of the lives of Imperial astropaths.

Also wrote a really good Necromunda story called Junktion which is practically a standalone work with little connection to what we see as 40k at large (not a single mention of the Emprah or Spess Mehreens or Xenos or the Inquisition or Chaos or ...), although this about fits for people who live out their whole lives in the forgotten holes of the Underhive. Also writes a bunch of short stories that wind up in anthologies, including some Eldar stuff, Sabbat Worlds and Iron Hands as well as some short Warhammer Fantasy works.

Happens to be one of the few authors for Black Library who does not live in the UK. In this case he is from the land down under. Contributed greatly to our perception of Angron through the story After De'shea, basically defining the at least slightly sympathetic modern perspective on the character as one with noble traits but seriously fucked over by grim darkness ranging from the Butcher's Nails to the seeming utter lack of pathos of the Emperor.

His short story The Memory of Flesh, about some post-Heresy Iron Hands fighting some obscure xenos with the ability to affect the nervous system of their enemies, is perhaps one of the most potent portrayals in 40k of how grimdark the whole concept sevitors, used by the putative good guys, actually is, not to mention the some general insight into the psyche (psychopathology?) of that most-underdeveloped Loyalist chapter.

Is not Steve Lyons.