Carl or Karl Heissler (18 January 1823 – 13 November 1878) was an Austrian violinist and violist.
He was studying with Joseph Hellmesberger, Sr., Matthias Durst and Joseph Böhm at the Academy of the Vienna music friends Society. In 1841 he entered the orchestra of the Vienna Opera and from 1843, he was also member of the Orchestra of the Imperial Court. From 1849, he played as second Violinin in the Leopold Jansa Quartet. Joseph Hellmesberger, Jr., the son of his professor founded a Quartet and dismissed Carl Heissler in order to take him in his group. The new group took the name of Hellmesberger Quartet. He taught at the Vienna Conservatoire, where his students included Julius Winkler, Arnold Rosé, Hans Wessely and Franz Schalk.
He was the first Director of the orchestral association of the Gesellschaft der Musikfreunde(1869) in Vienna. His successor was Anton Rubinstein (1871) then Johannes Brahms (1872).