I don't know how I missed this earlier today: http://www.guardian.co.uk/books/2012/aug/15/harry-harrison
Harry Harrison was one of my favourite SF authors as a teenager and young adult. His range of works from the comedic to intensely tragic was remarkable.
I think I've read all of the Stainless Steel Rat and Bill the Galactic Hero series at one point or another, along with many of his other books and short stories.
Harry - you will be missed.