Dušan Pirjevec, known by his nom de guerre Ahac (20 March 1921 – 4 April 1977), was a Slovenian resistance fighter, literary historian and philosopher. He was one of the most influential public intellectuals in post-World War II Slovenia.
Dušan Pirjevec was born in Solkan, which was then a suburb of the Italian town of Gorizia. His birth house is now located in the Slovenian town of Nova Gorica. His father was the literary historian Avgust Pirjevec from Gorizia; his mother, Iva née Mozetič, came from a wealthy merchant family from Solkan. His sister, Ivica Pirjevec, later became a famous anti-Nazi resistance hero and was captured and killed by the Nazis in 1944 (a street in the Ljubljana neighbourhood of Tacen in the Šmarna Gora District bears her name). Soon after Dušan's birth, the family moved to Ljubljana, in what was then the Kingdom of Serbs, Croats and Slovenes, where his father worked as the chief librarian of the National Research Library. Dušan attended the Ljubljana Technical High School, and in 1939 he enrolled to the University of Zagreb, where he studied agronomy. In 1940, he joined the Communist Party of Yugoslavia.