One of the best known names in Polish fantasy is Andrzej Sapkowski [Wikipedia], author of The Witcher series of short stories and novels [Wikipedia]. While the books were extremely successful in Poland and translated widely in Europe, it was only recently that an English-language edition has been made available.
Dark fantasy with a distinctly European flavour, the series has also spawned a tv series, a graphic novel series and even its own computer game. Gollancz first published Ostatnie życzenie – The Last Wish [Orbit paperback edition on Amazon.com] in the UK in 2007, which was followed by Blood of Elves in 2008 [Amazon.com] – and with a third title coming out this year.
Highly recommended (I read The Last Wish in proof form from Gollancz and loved it), and one of the rare examples of contemporary European fantasy making its way into the English-language world.