Ku Klux Klan

The Ku Klux Klan was a racist organisation in the United States of America in the 20th century. Klansmen believed immigration into the United States was out of control and immigrants would take jobs and homes away from white people. Furthermore, they opposed the end of segregation and believed black people were made as inferior to white people. Klansmen were recognisable by their pointed hood and white robes. (PROSE: Salvation)

In 1947, the Second Doctor and Ben Jackson saw Selyoids take the appearance of a hundred robed Klansmen on large horses fighting with Roman legions and the Los Angeles Police Department. (PROSE: Dying in the Sun)

Later that year, a Malean named Mykloz believed that racism was endemic to the United States and the Ku Klux Klan could become another Nazi Party under the influence of the Maleans. (PROSE: Playback)

In 1965, a New York City Klansman claimed their Imperial Wizard had proof that killings in Alabama were a Communist plot against the Klan. He accused President Lyndon B. Johnson of "besmirch[ing] the Klan's name" and discriminating against his own race. Three Klansmen believed the Latter-Day Pantheon were Gods who created black people to be inferior and asked them to spread their racist ideology. The Patriarch considered the offer, but grew weary of conflicting beliefs and ultimately drove the Klansmen away with a bolt of electricity and the threat of incineration. (PROSE: Salvation)

In 1970, CIA agent Thomas Bruce was as committed to UNIT as Civil Rights leader Martin Luther King was to the Ku Klux Klan. (PROSE: The Devil Goblins from Neptune)

In the 2000s, Captain Jack Harkness joked that Civil Servants secretly wore ceremonial bowler hats in private like an "administrative version of the Klu Klux Klan". (PROSE: Slow Decay)

Behind the scenes
Author Andy Lane misspelled Ku Klux Klan as Klu Klux Klan in Slow Decay. This could be interpreted as a slip of the tongue on the part of Captain Jack.