Stephen R. Donaldson has a good claim on being one of the fathers of modern epic fantasy. His novel Lord Foul's Bane, the first in the Chronicles of Thomas Covenant, the Unbeliever, was published in 1977 and is credited (along with Terry Brooks's The Sword of Shannara) with kick-starting the subgenre as we know it.
The Thomas Covenant series recently concluded with its tenth volume, but Donaldson is now back with a new fantasy trilogy, dubbed The Great God's War. The first volume, Seventh Decimate, will be a major hardcover release from Berkley Press in the autumn of 2017.
The trilogy will apparently chronicle a magical war and the quest by a prince to find a sorcerous library that holds the key to saving his kingdom. Knowing Donaldson, I suspect things will get radically more complicated than that before the end.
Donaldson has published fantasy outside of the Thomas Covenant series before, with his Mordan's Need duology, as well as a major space opera series, The Gap.