Krakow is now a UNESCO City of Literature. Here's a long list of authors who lived in Krakow.
Sławomir Mrożek, a playwright and native of Krakow, died last August.
'Basia Howard writes about Tadeusz Różewicz, Poland’s most translated author, considered by many to be of the same stature as Szymborska and Milosz.' Here's Różewicz's bio and a page about one of his translated collections of poetry (They Came to See a Poet). He studied in Krakow but has spent much of his life in Wroclaw.
Tadeusz Boy-Żeleński, an M. D., critic, and satirist, spent part of his youth in Krakow. He moved to Lviv, where he was among the professors who were massacred by the Germans in July, 1941.
Gabriela Zapolska was active in the theater scene in both Krakow and Lviv. Her play The Morality of Mrs. Dulska is available in English translation.
Józef Wittlin received some of his education in Lviv. He studied philosophy and linguistics in Vienna, where he befriended Joseph Roth, whose works he would translate into Polish. Wittlin also translated Homer into Polish. He was in the Austro-Hungarian army in WWI, which was the subject matter of his only novel, Salt of the Earth (reviewed in this pdf). In his diaries, Gombrowicz identified Wittlin with 'bourgeois demonism. ... He is a bourgeois who got the bourgeois pulled out from under his feet. In this lies his demonism'. G's diary contains more remarks on Wittlin, who also tuns up in the diary of Marc Szeftel (of Pnin fame). Wittlin eventually moved to New York.
The YIVO entry on Polish Literature has a photo of Wittlin with his wife in Lviv and ends with several brief bios of other Galician Jewish authors who wrote primarily in Polish, chief among whom was Bruno Schulz.