William Reinhold "Gatz" Hjortsberg (February 23, 1941 – April 22, 2017) was an American novelist and screenwriter, who wrote the screenplay of the film Legend.His novel Falling Angel was the basis for the film Angel Heart (1987). The novel was adapted into an opera in 2015, composed by J. Mark Scearce with a libretto by Lucy Thurber. Source: Wikipedia (en)