http://en.wikipedia.org/wiki/Donald_westlake
For those who don't know his work, he wrote at least 100 books, mostly crime; as Westlake he tended to give his stories a humorous slant, as Stark he specialised in hardboiled crime, with an anti-hero prepared to kill anyone who got in his way if it was the most expedient thing to do.
I was a big fan of both aspects of his writing, as may have been apparent a few weeks ago when I mentioned my delight in discovering that there were two Stark books I hadn't read. There's apparently one more book en route to publication, after that presumably it's over.
He'll be missed.