Juliusz Kleiner (April 24, 1886, Lwów – March 23, 1957, Kraków) was a Polish historian and literary theorist.

During the Soviet occupation of Lwów he retained his position at the University, teaching one of the few remaining courses in Polish.

In 1940 he succeeded in advocating his best scientific pupil Stefania Skwarczyńska to be released from labour camp in Kazakhstan.

Then during the Nazi occupation, Skwarczyńska hid him as "Jan Zalutyński" in the Teleżyński family (Wilkołaz in Lublin area) and later in the Żółtowski family (Milejów).

[2] In 1940 and 1941, Juliusz Kleiner advocated for the release of a Polish woman who had been deported to a forced labour camp in Kazakhstan.