I am seriously in love with Paul F. Wilson's Repairman Jack series. I'm trying to patiently await the newest one. It's kind of hard.

Robert Holdstock's books are also pretty awesome. They're loosely based off of the folklore and mythical stories of Jason of the Argonauts, Merlin and of course Medea.
Celtika & The Iron Grail
are the two I believe are part of that series.
Rosemary Sutcliff is also a great writer.