Muggles' Guide to Harry Potter/Magic/Giant

Overview
Giants are magical creatures which can grow to be over twenty feet tall. They are often described as being vicious and unintelligent.

Extended Description
There are very few giants left in the world, and those that do exist normally hide in the mountains where they are very rarely bothered by humans. Giants, unfortunately, need a large area to hunt, and they are not particularly social; forcing them all to live together in a restricted area typically results in fights between them, and fights between giants are quite often fatal. As a result, the Giant population is declining.

In the Harry Potter and the Order of the Phoenix, we learn that Hagrid and Madame Maxime were sent by Dumbledore to try to convince the giants to help them fight against Voldemort, but they were unsuccessful. The then-leader of the giants was overthrown, and his replacement was more aligned with the cause of the Death Eaters.

Before leaving the mountains, Hagrid finds his half-brother, Grawp. He brings Grawp back to Hogwarts and hides him in the Forbidden Forest. He introduces Grawp to Harry and Hermione because he is afraid he may soon be fired, and tells them that he has been trying to teach Grawp English. He extracts a promise from Harry and Hermione that, should he be sacked, they will continue Grawp's education.

In Harry Potter and the Half-Blood Prince, the Muggle Prime Minister mentions an apparent hurricane in the West Counties. Cornelius Fudge admits that it was a Giant, apparently one of Voldemort's, and the story of the hurricane was a fabrication of the Ministry to keep Muggles from learning that Giants exist.

In Harry Potter and the Deathly Hallows, at least two Giants are attacking Hogwarts in the final battle, and Grawp, who is revealed as being quite small for a giant, is defending.

Analysis
In the Harry Potter and the Goblet of Fire, we learn that Hagrid is a half-giant. His father was a wizard, but his mother was a giantess. Although she denies it, it is fairly obvious to the reader that Madame Maxime is a half-giant. It is unlikely that she would be able to reconcile with Hagrid if she was denying the giant part of her heritage, so the fact that she and Hagrid set off together seems to indicate that she has admitted, at least to him, that there is giant in her background.

In Harry Potter and the Order of the Phoenix, we learn that there are only about seventy to eighty giants left, and we also learn that they are located in the Eastern European mountains. Hagrid, who was traveling to the Giants' territory on foot, says that they had trouble with "a couple 'o mad trolls on the Polish border", and a "sligh' disagreement with a Vampire in Minsk", which, starting from Dijon, France, would indicate a roughly northeastwards trip into the Ural mountains north of Moscow.

Greater Picture
At the end of the Half-Blood Prince, we see Grawp attend Dumbledore's funeral. He seems to have become very tame.