Franz Petrak (9 October 1886, Mährisch-Weißkirchen – 9 October 1973, Vienna) was an Austrian-Czech mycologist. From 1906 to 1910, he studied botany at the University of Vienna, where he was a student of Richard Wettstein. In 1913 he obtained his doctorate of sciences, and until 1916, worked as a high school teacher in Vienna. During World War I, he was stationed in Galicia and Albania, where he collected specimens in his spare time. From 1918 to 1938, he worked as a private scientist in his home town, and from 1938 to 1951, was associated with the Naturhistorisches Museum in Vienna.