I have recently been revisiting the Black Templar Space Marines of the Solemnus Crusade for an upcoming (and rather unexpected) project and looked up my Templars short story Sanctuary which originally appeared in Inferno! magazine #38. The accompanying illustration of Chaplain Wolfram battling genestealers was by Dave Allsop and was a really rather fine piece of work.
So I looked him up on the Internet and found this... But be warned, it's not for the faint of heart. I particularly like his paintings of a Putrid Leech and a Tooth Golem along with his cute Cthulhu characters (that can be found here).