Born October 22, 1947 in Jefferson County, Kentucky, William Brent Girdler launched his filmmaking career with the 1972 release of Asylum of Satan. He made a total of nine films in six years and provided the music for the Pat Patterson quickie Dr. Gore. Girdler died in a helicopter accident in the Philippines after completing his final movie The Manitou.

Girdler wore many hats in respect to his filmmaking, writing six of his nine films and composing the music for three. He also produced two of his own movies. His early works were filmed in his hometown of Louisville, KY with the assistance of many friends and local investors. Girdler's first two low budget horror entries, Asylum of Satan and Three on a Meathook, made only a slight impact on the drive-in movie scene, but they got his foot in the door with Sam Arkoff and AIP. Girdler subsequently made three blaxploitation films: Zebra Killer, Abby, and Sheba Baby. After his AIP stint ended, Girdler directed the political thriller Project Kill starring Leslie Nielsen. Eager to return to horror, Girdler sought finances from Edward Montoro and thus brought Grizzly and Day of the Animals into the world. Girdler hoped to strike gold when he bought the rights to Graham Masterton's 1976 best-selling novel 'The Manitou' for $50,000, and he did just that. Within three months of securing the rights, Girdler began shooting the movie with Tony Curtis and Susan Strasberg in the leading roles.

William Girdler's most successful effort is Grizzly, a bleak Jaws knockoff starring a giant fuzzy bear. Made on a fairly tight budget, Grizzly ranked among the most successful films of 1976. Abby, a 1974 Exorcist rip-off which prompted a lawsuit from Warner Brothers, was also a box-office hit and made more money via domestic rentals than Blacula. Legal issues prevented Girdler from seeing profits for both films. Other box office hits born of Girdler include the Pam Grier vehicle Sheba Baby and The Manitou (a posthumous hit).