Harry Potter and the Order of the Phoenix
by J.K. Rowling
When Hagrid and Madame Maxine first find the giants in France, they meet with the chief Karkus. He doesn't speak English, but he has translators. He seems impressed with the gifts Dumbledore has sent him, and is willing to listen to Hagrid's efforts at diplomacy. But unfortunately, after only a couple of days of meetings, Hagrid finds that Karkus has had his head ripped off by the new Gurg (leader) of the giants, Golgomath. Hagrid points out that, "they're not meant ter live together, giants [...] Not in big groups like that. They can' help themselves, they half kill each other every few weeks" (20.127). So Karkus is a casualty of giant nature: the giants have been forced to live together in large groups because humans are taking over their lands. But they aren't supposed to be sociable by nature, so they're constantly tearing each other apart.