Ghoul

A ghoul is a monster from ancient Arabian folklore. Ghouls live in burial grounds and other uninhabited places. The English word comes from the Arabic name for the creature: الغول "ghūl", which literally means "demon". The "ghul" is a devilish type of jinn believed to be sired by Iblis.
The female form is given as "ghouleh" in Muhawi and Kanaana (see ref below). The plural is "ghilan".
"Ghoul" is also a shapeshifting demon that lives in the desert. The demon can take the form of an animal, especially a hyena. It lures unwary travellers into the desert. It will then kill and eat them. The creature also preys on young children, robs graves, and eats the dead. Because of this habit the word "ghoul" is sometimes used to refer to an ordinary human such as a grave robber, or to anyone who likes the macabre. 
The star Algol takes its name from this creature.
In Iran.
In Iranian mythologies, Ghouls are creatures very similar to humans, but larger. Usually they are less intelligent and not necessarily evil.
Most Persian speakers use Ghoul to describe large people (figuratively "giants"). This may or may not be considered an insult, depending on the situation.
How ghouls are shown.
Ghouls and ghoul-like creatures have been portrayed in different ways in fiction, including a series of dark fantasy, short stories by Brian McNaughton, a Michael Slade novel, "Ghoul", Larry Niven's "Ringworld" series, J.K. Rowling's Harry Potter series, "The Chronicles of Narnia", the works of Caitlín R. Kiernan, Laurell K. Hamilton's Anita Blake series, and Jim Butcher's The Dresden Files.
Literature.
Morlocks are a fictional species of cannibalistic ghouls, created by H. G. Wells for his 1895 novel, "The Time Machine". The Morlocks, as well as another supposed offshoot of humans, the , exist in the future world in the year 802,701 A.D. in "The Time Machine".
Bram Stoker's 1897 novel "Dracula" has a character that acts much like a ghoul. The character is named Renfield. Under the vampire's influence, Renfield becomes his willing slave. He develops a craving to eat living creatures in the hope of obtaining their life-force for himself. After being confined to an asylum, he considers eating a human hospital orderly, but finds he can only capture and consume flies, spiders, and the occasional bird.
In the fiction of H. P. Lovecraft, a ghoul is a member of a nocturnal race that lives underground. Some ghouls were once human, but a diet of human corpses, and perhaps the tutelage of proper ghouls, changed them into horrific bestial humanoids. In the short story "Pickman's Model" (1927), the first of Lovecraft's ghoul stories, they are unutterably terrible monsters; however, in his earlier novella "The Dream-Quest of Unknown Kadath" (1926), the ghouls are somewhat less disturbing, even comical at times, and both helpful and loyal to the protagonist. Richard Upton Pickman, a noteworthy Boston painter who disappeared mysteriously in "Pickman's Model", appears as a ghoul himself in "Dream-Quest". Similar themes appear in "The Lurking Fear" (1922) and "The Rats in the Walls" (1924). Both of stories claim there are subterranean clans of degenerate, cannibals or carrion-eating humans.
In modern and contemporary fiction, ghouls are often confused with other types of undead, usually the mindless varieties of zombies. Although modern fiction (post-1954), particularly 1954's "I Am Legend", suggests that the latter beings share cannibalistic habits with ghouls, it is nonetheless generally believed that vampires and zombies prefer live prey.
In 's Dune series, a "Ghola" is a deceased person who has been brought back to life, via a secret, almost illegal Tleilaxu technology. Traditionally, the "Ghola" is stripped of memories from his or her past life and taught new skills. "Ghola" are often sold to nobles by the Tleilaxu as servants and retainers. Given their highly superstitious nature, Fremen are distrustful of ghola, despite the potential usefulness of the living dead. The ambiguity as to whether or not latent memories of the "old self" are still present in the ghola's mind is a long-drawn debate throughout the story. It has been suggested that the term "ghola" originates in Arabic, as do other terms in the Dune series.
Movies and television.
Although many screenplays have featured ghouls, the first major motion picture of this theme was the 1933 British movie entitled "The Ghoul". The actor Boris Karloff plays a dying Egyptologist who possesses an occult gem, known as The Eternal Light, which he believes will grant immortality if he is buried with it, and thereby able to present it to Anubis in the afterlife. Of course, his bickering covetous heirs and associates would rather keep the jewel for themselves. Karloff vows to rise from his grave and avenge himself against anyone who meddles with his plan, and he keeps this promise when one of his colleagues steals The Eternal Light after his death.
In 1968, George A. Romero's movie "Night of the Living Dead" combined reanimated corpses (zombies) with cannibalistic monsters (ghouls). With this, it created new movie monsters more terrifying than either of the two alone. The term "ghoul" was the one actually used in the movie. The term zombies came later, after the movie was released. Romero had never thought of them that way; he said he thought of the Caribbean creatures, when he heard the term "zombies".
The 1976 Turkish movie 'Milk Brothers' (original story by H. Rahmi Gurpinar's 'Ghoul') is a Turkish comedy. Here, a ghoul is a monster with extra power. Ghoul is a monster that was used to frighten little children in the old times, so here the ghoul is used to frighten not only little children, but as well big people.
The 1975 British movie "The Ghoul" (unrelated to the Karloff movie) stars Peter Cushing as a defrocked missionary whose son has developed a taste for human flesh while traveling in India. As the son's mind and body degenerate, Cushing has several young people dispatched and prepared as food for his offspring, whom he keeps locked up in the attic.
The 1975 anthology movie "The Monster Club" featured a scene where a village of ghouls stumbled upon by an unwary traveller (Stuart Whitman), who temporarily escapes the creatures with the help of one half-human girl, but he is recaptured when it turns out that the ghouls have representatives inhabiting our normal human world.
In the anime and manga series "Hellsing", ghouls are zombie-like creatures that are created when a "chipped" (technological) vampire drains a victim to death, or, in the Manga, where a vampire drains the blood of someone who is not a virgin. If fatally wounded, they instantly crumble to dust. They are under the control of the vampire who bites them, eat human flesh, and are intelligent enough to use firearms. It is not rare to see a vampire make a small army of Ghouls for attack or defense.
"The Ghoul" is the stage name of Cleveland-area horror television host Ron Sweed.
The Batman comics-based franchise, including the 2005 movie, "Batman Begins", has an antagonist named, Rā's al-Ghūl, whose name derives from the original Arabic name for the star Algol in the constellation Perseus meaning "the monster's (i.e. Medusa's) head".