Dan Abnett
Dan Abnett is the most popular author of Games Workshop paper book publishing division, the Black Library.
Series include Gaunt's Ghosts (good but repetitive), Eisenhorn (fantastic but emo) and Ravenor (Eisenhorn's love child so emo he lives in a metal cage).
Dan is known for fun action writing and rampant sodomy of Warhammer fluff, like Imperial Guardsmen toting around Autocannons the size of a howitzer.
His graphic novel Imperial Gothic is pure sex.