A misanthrope is a person who hates or mistrusts other people. Your great aunt Edna who lashes out at anyone who approaches, convinced they'll steal the jewelry she keeps in her handbag on her lap? A misanthrope indeed.
This is a formal word, derived from Greek misanthrōpos "hating mankind," from misein "to hate" plus anthrōpos "a man." From the same root, we get the English word anthropology "the study of humans." If you make a statement or do something that is particularly hostile or untrusting, you can call that misanthropic.