Amos Hackshaw was the principal antagonist of the H.P. Lovecraft pastiche Cast a Deadly Spell. He was portrayed by David Warner.
Hackshaw was a wealthy warlock living in Los Angeles in 1948. He was the father of Olivia Hackshaw. His wife had been dying of an illness and the family moved to California hoping the climate would help. It didn't, and Hackshaw's wife died. A worshiper of the Great Old Ones, Hackshaw discovered the Necronomicon while in Egypt, and planned to use a ritual contained therein to summon forth the ancient gods into the world. He planned to use his virgin daughter as a sacrifice, to this end keeping her away from men.
His chauffeur, Larry Willis, stole the Necronomicon - both the real one and a duplicate one with blank pages Hackshaw had made for the insurance company. Enraged and wanted the book back, Hackshaw hired private detective H. Phillip Lovecraft. He specifically sought Lovecraft out because the detective advertised himself as a non-magic user; Hackshaw knew a magic user would know what the Necronomicon was and be on to him.
Because Lovecraft didn't understand the book's significance however, Hackshaw was able to fool him into believing it was merely an ordinary book. As to Willis, he made up a story about the chauffeur having been fired for making a pass at Olivia. To ensure Lovecraft's success in obtaining the book and also keep a close eye on him, Hackshaw brought to life a stone gargoyle to serve him and follow Lovecraft. He intended for the beast to kill Lovecraft once he had outlived his usefulness and bring the Necronomicon back to him.
Unaware of this, Lovecraft reported back to the warlock when he discovered Willis had taken the Necronomicon for Harry Bordon. The gargoyle failed to get the get book and kill Lovecraft, however it did kill Willis. Lovecraft recognized the gargoyle from Hackshaw's mansion, and so did not take the book back to him. However, Harry Bordon, who had similar goals to Hackshaw, called the warlock and made a deal with him: he'd get him the Necronomicon and allow Hackshaw the use of Vista Bonita as the summoning ground if Hackshaw let him share in the glory. Hackshaw agreed.
Bordon, his zombie bodyguard and Connie Stone brought both Lovecraft and the book to Vista Bonita. Hackshaw came with his daughter, as well as a police detective, Otto Grimaldi, who'd been assigned to protect her, tied up in his Rolls-Royce. After Connie shot Bordon, Hackshaw used his powers to take command of the crime lord's zombie, and began the ritual. He successfully summoned Yog-Sothoth and tried to give him Olivia.
However, unknown to the warlock, she and Detective Grimaldi had had sex before he took them prisoner; Yog-Sothoth rejected Olivia as a sacrifice and in a rage ate Hackshaw alive before returning to the depths.