A hate group is a social group that advocates and practices hatred, hostility, or violence towards members of a race, ethnicity, nation, religion, gender, gender identity, sexual orientation, or any other designated sector of society. According to the United States Federal Bureau of Investigation (FBI), a hate group's "primary purpose is to promote animosity, hostility, and malice against persons belonging to a race, religion, disability, sexual orientation, or ethnicity/national origin which differs from that of the members of the organization."

The Ku Klux Klan, commonly shortened to the KKK or the Klan, is the name of several historical and current American white supremacist, far-right terrorist organizations and hate groups. According to historian Fergus Bordewich, the Klan was "the first organized terror movement in American history." Their primary targets, at various times and places, have been African Americans, Jews, and Catholics.