Not Graeme Lyon.
In all seriousness, Chris Wraight is a newer Black Library writer, and so far he doesn't disappoint.
His works so far consist of:
Single handedly made White Scars and Jaghatai Khan awesome and popular, because lets be honest, how many of you ever cared about them before his books.
Killed off Dan's fuck up.
Wrath of Iron, another Space Marine Battles novel, where the Iron Hands fight the forces of Slaanesh while being extremely awesome, though also being massive dicks in the process. Nice to see the Iron Hands getting some time in the spotlight.
Iron Company, a WHFB novel I haven't read. But I (another writer) has, and it is a top level novel: no chaos bullshit, just guns and sword, pure Rip & Tear, very good book. Also Sword of Justice and Sword of Vengeance, both are pretty damn good WHFB books focused on Ludwig Schwarthelm and Kurt Helborg, both are pretty damn badass.
Kraken, a Space Wolves short story about a bunch of humans on an water world getting their ship-cities wrecked by mysterious sea monsters who call on space Marines for help, but get a lone wolf instead. Some minor but noteable lulz when the people can't quite understand how the fuzzy faced giant covered in pelts could be a space Marine.
Brotherhood of the Storm, a recent limited edition Horus Heresy novella about the White Scars and the event that caused Horus to mistakenly assume the Khan would join him.
Scars, a full length Horus Heresy novel following the Khan as he decides whether to side with Horus or the Emperor.
Path of Heaven, a sequel to Scars that gets right into the fatalism and misery of the late Heresy, as well as the shenanigans involved in the Webway project. Manly tears occur.
Blackshield, a short story about an ex-Deathshroud renegade. Along with Demonology and the Death Guard appearances in the WS novels, he's probably going to write the downfall of Mortarion.
Leman Russ: The Great Wolf, a Heresy-era novel about, you guessed it, Russ.
Valdor: Not to be confused with Valedor by Guy Haley (notable for having not one but TWO Avatars of Khaine actual kick ass), the book is set right at the end of the Unification Wars. It has surprisingly few chapters centered on the titular Captain-General, but it has a fun espionage vibe. Also stars an awesome battle between Valdor and a Thunder Warrior.
He has a Space Wolves short story and two full Space Wolves novels out and they're all pretty good. Blood of Asaheim and the following Stormcaller novels are both standout grimdark that bridge the gap between William King's happy-go-fluffy wolves and the thinly stretched, stubborn bunch of rip and tear fucks we know them to be.
He's also written 'Jaghatai Khan: Warhawk of Chogoris' for the Primarchs series of HH novels. This should deal with the founding of the Librarius.
He wrote Watchers of the Throne and its related books Carrion Throne and The Emperor's Legion. All three provide a really good look at the Custodes, Sisters of Silence, and the High Lords of Terra, managing to provide some much-needed fleshing out to all three factions. It also moves the Custodes away from their Master of Mankind characterisation as heartless stone cold bastards and elaborates on their overall organisation and modern-day deeds, as well as making the High Lords sound at least competent. The Sisters (especially Aleya, when she's not complaining about how shitty the Imperium is and being salty over her sisters getting abandoned) are also very cool.
He wrote Bloodlines, the first book in the Warhammer Crime series in which an overworked cop on an Imperial World gets wrapped up with a plot involving Nobles and Gangs following an missing person case. If you ever want a good insight as to what Civilian Life is like in the Imperium of Man, this delivers.
Chris also wrote The Lords of Silence which gives insight into how post Heresy Death Guard function and how they view Mortarion. It also will make you find the Nurglings even more adorable. On the other hand, this book also claims that all Agri-Worlds are dustbowl-esque hellscapes where even fucking crop rotation isn't used, so fail there.
His biggest strength so far seems to be fleshing out Legions and other factions who've had very little love previously. A lot of people who never liked the Scars have been won over by his portrayal, and he's even done a good job on the Emperor's Children and Death Guard as antagonists, midway through and still putting off Chaotic corruption, respectively. He's made Eidolon competent whilst not just turning him into a totally new character. Also wrote the first proper description of Terra itself in Carrion Throne, and it is AWESOME.