Dystopias: When the World Goes Wrong

I love a good dystopia. By which I mean, of course, a book set in a very dark version of the future rather than in an idealized (utopian) one. Some dystopias project present trends or the author's worst fears quite far into the future. For example, Brave New World shows a society in which genetic engineering plus entertainment have achieved a very advanced level of control over humanity, far more so than was the case at the time of writing. Other dystopias are actually about the present day. 1984 was originally meant to be titled 1948, and to be a description of life under a totalitarian regime that is constantly at war, which was of course already happening at the time. Similarly, Lord of the Flies, about the descent into barbarism of a group of boys stranded on a remote island, was apparently a critique of the adults, who were fighting a world war back in "civilization." Other classic dystopias, which they tended to make us read in high school, include Fahrenheit 451 and Animal Farm. The genre is alive and well, and it seems that new dystopias are being written every year. Lois Lowry has written some terrific ones, such as The Giver and Gathering Blue. There is Agenda 21, which has Glenn Beck's name on the cover but was actually written by Harriet Parke, where the future is one of regimented, cultureless starvation brought about by environmentalist totalitarians. On the other end of the spectrum, The World Made By Hand and The Witch of Hebron by James Howard Kunstler bring to well-written life his vison of a future in which oil shortages, plagues, and an energy crisis have returned North Americans to a preindustrial lifestyle within one generation. (See, you can write a dystopia from any point of view!) A very good recent dystopia was The Office of Mercy by Ariel Djanikian, in which one group of human beings exterminates another group at the slightest sign of suffering. That one will make you cry. Dystopias, especially the classic ones which do not tend to have happy endings, are not good beach reading. They will wrench you, haunt you, and stay with you for weeks. But they tend to be intense page-turners, as well as being an important source of wisdom about our world. So what have I missed? What's YOUR favorite dystopia?