I want to introduce my absolute favorite in commercial BDSM-pulp: the late F.E. Campbell.
He published over one-hundred paperbacks for the BD-specialist "House Of Milan" (HOM now Lyndon Distributors) with cover-art by the legendary "Bishop".
He never wrote really hardcore stuff,but I consider his sophisticated style and language as highly erotic. In his books he visited settings like kinky boarding schools and reformatories ("Monica", "Iron Bars & Love", "The Lash of Maiden Hall"), Mid-East harems and slave-markets ("The Prisoner Of Ismaul", "Slaves of Jehdra", "Dungeons Of Hagadar"), Southern plantations ("Susan") etc. etc.
He also published a series of sixteen novelettes about the sadistic butler "Fellowes", illustrated by "Ashely". (Today you can find these Ashely-drawings in many BDSM-Art-collections of the www ,for example in the members' area of the "Library".)
In his old-age he lost his eye-sight, so that the last ten novels published under his name were ghost-written by his successor John Savage (also a fine author but not as good as Campbell)
Unfortunately most of Campbell's work is today out-of-print and very hard to get.
Let's hope for an E-book-reissue...

So and who is your favourite commercial author?