I'll pipe up for another, the dazzlingly imaginative Bruno Schulz. His work is half an evocation of his family's life in a small early 20th-century Polish city, and half cosmic and out-there. He's like a Polish Kafka, but more whimsical, less austere. He haunts his own writing like a ghost because of his shocking death and the fact that his major work was lost. This adds poignancy to reading him that wouldn't otherwise be there, like a painting that was damaged in a way that became part of the art and made it a different whole.
Two other Polish modernists that I've been meaning for years to read are Gombrowicz (Ferdydurke) and Witkiewicz (Insatiability). Both are said to be fabulous.
There's a recent translation of Ferdydurke that's supposed to be good. Be careful not to get the earlier translation, which was translated indirectly from a French intermediate and really doesn't have much to do with the original as a result.
Re-reading Heart of Darkness as an adult was a totally different experience from the forced read of it as a child.
I also really enjoyed Conrad's Nostromo, a true masterpiece.
http://en.wikipedia.org/wiki/Ryszard_Kapu%C5%9Bci%C5%84ski
His most known book:
http://en.wikipedia.org/wiki/The_Emperor_(book)