In real life, the zombies come from the Caribbean island of Haiti. They are a person who has been almost-killed, and then later raised from the almost-dead by a voodoo priest, to be used as slave labour for the rest of their miserable life. Zombies can move, eat, hear and speak, but they have no memory and no insight into their condition. There have been legends about zombies for centuries, but it was only in 1980 that a real-life case was documented.
The story begins in 1962, in Haiti. A man called Clairvius Narcisse was sold to a zombie master by his brothers, because Clairvius refused to sell his share of the family land. Soon after Clairvius "officially" died, and was buried. However, he had been later secretly unburied, and was actually working as a zombie slave on a sugar plantation with many other zombies. In 1964, his zombie master died, and he wandered across the island in a psychotic daze for the next 16 years. The drugs that made him psychotic were gradually wearing off. In 1980, he accidentally stumbled across his long-lost sister in a market place, and recognized her. She didn't recognise him, but he identified himself to her by telling her early childhood experiences that only he could possibly know.
Dr. Wade Davis, an ethnobiologist from Harvard, went to Haiti to research this story. He discovered how to make a zombie. First, make them "dead", then make them "mad" so that their minds are malleable. Often, a local "witch doctor" secretly gives them the drugs.
He made the victim "dead" with a mixture of toad skin and puffer fish. You can put it in their food, or rub it on their skin, especially the soft, undamaged skin on the inside of the arm near the elbow. The victims soon appear dead, with an incredibly slow breath, and an incredibly slow and faint heartbeat. In Haiti, people are buried very soon after death, because the heat and the lack of refrigeration makes the bodies decay very rapidly. This suits the zombie-making process. You have to dig them up within eight hours of the burial, or else they'll die of asphyxiation.
The skin of the common toad (Bufo bufo bufo) can kill - especially if the toad has been threatened. There are three main nasties in toad venon - biogenic amines, bufogenine and bufotoxins. One of their many effects is that of a pain-killer - far stronger than cocaine. Boccaccio's medieval tale, the Decameron, tells the story of two lovers who die after eating a herb, sage, that a toad had breathed upon.
The other half of the witch doctor's wicked potion comes from the pufferfish, which is known in Japan as "fugo". Its poison is called "tetrodotoxin", a deadly neurotoxin. Its pain-killing effects are 160,000 times stronger than cocaine. Eating the fish can give you a gentle physical "tingle" from the tetrodotoxin - and in Japan, the chefs who prepare fugo have to be licensed by the government. Even so, there are rare cases of near-deaths or actual deaths from eating fugo. The toxin drops your temperature and blood pressure, and puts you into a deep coma. In Japan, some of the victims recovered a few days after being declared dead.
Back in Haiti, once you've got the zombie-in-waiting out of the ground, you make them mad, by force-feeding them a paste made from datura (Jimsons Weed). Datura breaks your links with reality, and then destroys all recent memories. So you don't know what day it is, where you are and, worst of all, you don't even know who you are. The zombies are in a state of semi-permanent induced psychotic delirium. They are sold to sugar plantations as slave labour. They are given datura again if they seem to be recovering their senses.
Datura (Jimsons Weed, Angel's Trumpet, Brugmanisa candida) contains the chemicals atropine, hyoscyamine and scopolamine, which can act as powerful hallucinogens in the appropriate doses. They can also cause permanent memory loss, paralysis and death.
The person who applies these chemicals to a victim has to be quite skilled, so that they won't kill them. There is a very small gap between appearing-to-be-dead, and actually being dead.
So make sure that before you use a priest or witch doctor, you ask to see their qualifications... Lol