What word is used to describe someone who has a hatred or mistrust of mankind?

The term that describes someone who harbors a hatred or mistrust of mankind is "misanthrope." This word originates from the Greek roots "misein," meaning "to hate," and "anthropos," meaning "human." A misanthrope often expresses a general disdain for human society and the behaviors of individuals within it, often believing that people are selfish or morally flawed.

In contrast, a philanthropist is someone who seeks to promote the welfare of others, particularly through charitable donations and actions. An activist is a person who campaigns for social or political change, working to improve societal conditions rather than expressing hatred towards humanity. An altruist refers to someone who is selflessly concerned for the well-being of others, placing the needs of others above their own interests, which is fundamentally different from the sentiment of mistrust or hatred found in misanthropy. Thus, "misanthrope" precisely encapsulates the feeling of disdain for humanity, making it the correct choice.