The undefeated champion of the "most fantasy-esque name I've ever heard of" contests at Games Workshop every year, Lucien Soulban has written quite a bit of stuff for the tabletop gaming industry as a whole. Born in noted totalitarian hellhole and inexplicable American ally Saudi Arabia and residing in the also hellish and inexplicable place known as Texas, he's one of the rare non-British writers for the Black Library.
Being actually from Arabia also meant that his old novel Desert Raiders is basically drenched in authentic Arab cultural references. Whereas the cultural references of most guard regiments are fairly skin deep, he very firmly reminds you that the Tallarns are highly religious space arabs, even calling the Emperor the Aba Aba Mushira, as well as mad geniuses when it comes to using vehicles and ambush tactics. Also of course, many pages spent on the importance of water to desert cultures.
He also gives the Tyranids one of their rare wins in Black Library novels, with the Tallarn forces in the book desert raiders holding out bravely but ultimately all getting eaten by the Tyranid swarm.
He is not Guy Haley