The giants in mythology are primordial creatures of enormous size, the personifications of the forces of nature. They usually are the enemies of humans and often battle the gods (such as the Greek Titans, the Irish Fomorians and the Norse giants of Jotunheim). Giants frequently play a significant part in the Creation Myths. They existed long before the gods and humans came. With the appearance of gods there followed a struggle between the two, in which the giants got the worst of it. When a giant was slain by a mighty god, the god would create heaven and earth from the giants body. Even in the bible there are references to giants. In Genesis it is said that "in those days there were giants in the earth" and of course there is the story of David and Goliath, although the latter can hardly be considered a giant, being only 3 meters (9,8 ft), when compared to the giants in mythology and folklore.
There are many fairy tales in which giants appear. Those giants are usually very stupid, greedy and fond of human flesh. Often a resourceful young man (named Jack) is able to kill or defeat the giant (Jack and the Bean Stalk, Jack the Giant Killer). However, not all the giants are evil; in some tales they are kind beings, who befriend little children. Trolls, and ogres are good examples of these monsterous creature.