 Between 1974–76 he performed at the Viennese Volkstheater, then went on to the Thalia-Theater in Hamburg before returning to Austria in 1978 and joining the Viennese Burgtheater's ensemble, where he soon became a crowd favourite.In 1988, Hackl debuted as theater director at the Volkstheater.He frequently appeared in movies and television series and worked with the likes of Axel Corti and Alan J. Pakula ("Sophie's Choice").