Looking much like humans do but of much larger proportions, usually hostile and with a taste for human flesh, giants had have a common role to play in many mythologies: the bad guys. Nonetheless, most representations of giants in modern literature and film come from European folktales and legends.
Among the many types of giants, cyclopes occupy a privileged site. The Greek word "cyclops," which means "circle-eye" or "round-eye," refers to a race with only one eye situated on the center of their forehead just upon the nose. Famous among the cyclopes is Polyphemus, Odysseus's monocular nemesis, who was of huge size, gifting such characteristic on his entire race.
Ogres and trolls are varied kindred. Ogres are common antagonist for the heroes of fairy tales, while trolls appear in numerous romances and legends.
Outside Europe, giants also appear in folktales, notoriously in the Middle Eastern folktales collection One Thousand and One Nights, compiled during the Islamic Golden Age, djinns (referred in Western literature as genies) appear to be much taller than the average man. As such, djinns, had acquired more gigantic proportions, and in recent times, are usually portrayed in fantasy fiction and film as enormous beings, always capable of growing even more at will.
Among children, one well known giant is the ogre who appears in Little Thumbling, one of the eight fairy tales published by Charles Perrault in 1697. This ogre allows Little Thumbling and his brothers to spend the night at his house, hence saving them from the hungry wolves waiting in the woods. However, his actions are not motivated by kindness but by gluttony, since all he wants is to kill the children in their slumber and eat them. Of course, as size isn't all, Little Thumbling uses some street smarts to trick the ogre into eating his own three daughters.
While giants seem more a thing of the past, various kinds of them, some even benign, appear in such modern works of fiction as Poul Anderson's Three Hearts and Three Lions (1961), where Holger Carlsen, a twentieth-century man, is snatched out of time to become again the legendary Holger Danske and fight against giants and other creatures. Similarly, Charle's de Lint's Jack the Giant-Killer (1987) introduces Jacky Rowan, a young woman from Ottawa, who after picking up a magic red cap is able to see into the Faerie realms, becoming the only hope for victory against the forces of evil, and quite some giants.
But giants are not always made of flesh and bone. As society changes, its myths and legends evolved, and as folktales turn to bedtime stories the once evil giants become benign creatures, some of them not born but made. And example of this is Ted Hughes's The Iron Man: A Children's Story in Five Nights (1968), where The Iron Man, a mechanical giant, arrives seemingly from nowhere to become the unlike friend of Hogarth, a local boy, and save the Earth from a fiery dragon. This novel, was translated to film as The Iron Giant (1999), which, arguably, surpassed the popularity of the original work.
In Norse mythology, giants are often opposed to the gods, as well as being the origin of various monsters, like the monstrous wolf Fenrisulfr. Eventualy, in battle of Ragnarök, it's said that the giants will storm Asgard and fight the gods until the world is destroyed.
In Bulgarian, as in many other mythologies, giants represent an ancient race that inhabited the Earth before modern humans. These giants tipically lived in the mountains, fed on raw meat and often fought against dragons.
-Pringle, D. (Ed). 2006. The Ultimate Encyclopedia of Fantasy. Carlton.