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Misanthrope: Someone who hates mankind and/or avoids human society.

eg "Hey, this coffee machine must've been made by a complete misanthrope."

A brief trawl through the blogosphere will reveal many misanthropes.

Interestingly, there is an inverse relationship between how misanthropic someone is, and their urgent need to communicate to as many people as possible, ie the more they hate everyone, the less they can keep their damned mouths shut (see Politicians).

NB
For reasons of political correctness, some authorities now prefer the term 'Ms. Anthrope'.