Author: Wim Gijssen, a science fiction and fantasy author who sadly enough passed away in 1990, but who very successfully mixed science fiction and fantasy into three series of books.
Titles: 'De Eersten van Rissan' + 'De Koningen van weleer' (translated into English as 'The First Ones of Rissan' + 'The Kings of the Past'); 'Iskander de Dromendief' + 'Het Huis van de Wolf' (translated as 'Iskander the Dream Thief' + 'The House of the Wolf'); and the third series which is, as fas as I know, not translated: 'Keerkringen' + Bidahinne' + 'Lure'. (translations of the titles courtesy of Wikipedia).
The books all play on distant planets where centuries ago people from earth settled, gradually lost all knowledge about technology and a society evolved around magic, mysticism and remnants of technological prowess.
Another author who features on my book shelves is the Dutchman Michiel Nijk, with the book 'Vrije Val', a fairly harsh science fiction thriller. He is also the author of 'De Heersers van Kant' which I have read but couldn't keep (libraries can be cruel some times), which is more a mixture of the harsh science fiction and a bit of fantasy, if I recall correctly. I have searched English versions of these books for my wife but I don't think The Netherlands is the best place to go looking for translated versions of Dutch books.
A classic in The Netherlands is the book 'Beekman en Beekman' by the author Toon Kortooms. A hilarious story about the lives of two twins who get up to all sorts of shenanigans.
By Courtesy of Theo Bernards