Waxwork

In a small suburban town, a group of college students "Mark, China, Gemma, James, Tony, and Sarah" visit a mysterious wax museum, where they encounter several morbid displays, all of which contain stock characters from the horror genre. Tony and China enter two separate waxwork displays. Tony is at a cabin where a werewolf attacks him. A hunter and his son come, suppressing their fear. The son fails and is torn in two, while the hunter shoots the werewolf, and Tony as he begins the transform. China is sent to a Gothic castle, where vampires attack her and Count Dracula turns her into a vampire. Two of the other students, Mark and Sarah, leave the waxwork unscathed, later Johnathan "a college jock" comes in to the Wax Museum looking for China, but the Phamton of The Opera display got his attention as David Lincoln walked him into the display, Mark goes to a pair of investigating police detectives, Inspecter Roberts meets Lincoln as he lets Roberts investigate the Waxworks, as Mark and Roberts leave the Museum, Mark reconized Lincoln.later, Roberts realized some of the displays looked like some of the other missing people, and then comes back to the Wax Museum, as he cuts off a piece of China's face and puts it in a bag, then he walks into the mummy display as the mummy throws him in the tomb to be killed by a snake, later, Roberts' partner sneaks in and gets his neck broken by Junior "a tall butler" Lincoln scolds him for killing the partner.Mark takes Sarah to the attic of his house, where he shows her an old newspaper detailing the murder of his grandfather (which was seen in the prologue); the only suspect was David Lincoln, his chief assistant, whose photograph closely resembles the waxwork owner. The two then consult the wheelchair-bound Sir Wilfred, a friend of Mark's grandfather, who explains how he and Mark's grandfather collected trinkets from "eighteen of the most evil people who ever lived" and that Lincoln stole the artifacts; Lincoln, having sold his soul to the devil, wants to bring their previous owners to life by creating some wax effigies and feeding them the souls of victims, a concept taken from voodoo. Providing all eighteen with a victim would bring about the "voodoo end of the world, when the dead shall rise, and consume all things".On the advice of Sir Wilfred, Mark and Sarah enter the waxwork at night and douse the museum with gasoline. However, Sarah is lured into the display of the Marquis de Sade, and Mark is pushed into a zombie display by the waxwork's two butlers. Mark is approached by a horde of zombies, but finds that if he does not believe in the monsters, then they do not exist and cannot harm him. Mark finds his way out of the display and into the Marquis de Sade exhibit, where he rescues Sarah, while the Marquis vows revenge.Despite Mark and Sarah's attempts to escape, Junior and Lincoln grab Mark and Sarah pull them out of sight as Gemma and James returned, Gemma gets lured into the Marquis de Sade display and James attempts to steal something from the Zombie display, as the bodies of James and Gemma reappear as wax figures, the displays are completed with the figures and their victims reanimating as evil entities. Suddenly, Sir Wilfred and a huge group of armed men "along with Mark's butler Jenkins" arrive and in the ensuing battle, several waxworks and slayers die, including Lincoln's butlers and Mark and Sarah's former friends, now evil. Mark duels with the Marquis de Sade, who is finally killed by an axe, wielded by Sarah.The reunited couple is confronted by Lincoln, who dies getting shot by Sir Wilfred and falls in a vat of boiling wax. Sir Wilfred is killed by a werewolf as Sarah and Mark manage to escape the burning waxwork with their lives and begin to walk home, not noticing that the hand from the Zombie display is scuttling away from the rubble.

Question: How many evil people did Mark's grandfather collect trinkets from?
Answer: Eighteen