Racism
Racism was the belief that one race was inherently superior or inferior due to certain characteristics, be they physical (for example skin, eye, or hair color, or the genetic makeup of one's species) or cultural (such as a race's language, philosophy, religion, traditions, or level of technological development). Insults based in racism were known as racial slurs.

Racism on Earth
Earth regions that experienced racism included the United States of America in the 19th and 20th centuries and Germany under the Nazi regime. (; ; )

The Ku Klux Klan, a white supremacist group, was notorious for its racist views. ()

Benny Russell faced racism in 1950s New York City when he attempted to get his story published in Incredible Tales magazine, as it had a black captain in command of a space station. Douglas Pabst imagined it would take fifty years or more from that point for the Human race to become color blind (look beyond one's skin color). ()

When Vic Fontaine's program was affected by the jack-in-the-box laid in it by programmer , Benjamin Sisko admitted to Kasidy Yates that he eschewed the holo-program because he felt it ignored the suffering of African-Americans during the time period in which it was set. ()

The 23rd century
In the 23rd century, the natives of the planet Cheron conducted a devastating war based solely on the racial differences of its inhabitants. While both races of their planet were half white and half black, the sides of their body which displayed those colors varied. As a result the ruling class, which was white on the left side and black on the right, suppressed the other race in which the coloration was reversed. By 2268, the racial campaign by the ruling class and rebellion by the oppressed had rendered the planet nearly uninhabitable. ()

During the same century, as a result of his mixed Human/Vulcan heritage, Spock was the subject of constant discrimination, teasing, and ostracism during his youth by his full-Vulcan classmates, which apparently at least once descended into actual physical abuse; this could have been seen as racism. (; ) This continued while Spock served on the , during which Dr. Leonard McCoy referred to him, as, among other things, "pointy eared", "green blooded", and a "hobgoblin."  This was done more due to McCoy's frustrations with Spock himself than any real dislike of the Vulcan people, and sometimes even as friendly jibes or even nicknames. While Spock generally appeared to be immune to the insults, one time Spock temporarily lost his emotional control and reacted with anger to McCoy's words, to the point of lifting McCoy up against the wall by his throat. ()

 also suffered this discrimination in the alternate reality, during which his classmates repeatedly cajoled him and insulted both him and his parents in order to elicit an emotional response from him. This culminated in an incident on the bullies' 35th attempt in the alternate 2243, when Spock viciously attacked the ringleader of the bullies after they referred to his  as a "traitor" and his  as a "Human whore". Spock was also discriminated against by the selecting committee of the Vulcan Science Academy, who congratulated him on overcoming the "disadvantage" of his mixed heritage and gaining entry to the academy despite that disadvantage. Upon hearing this, Spock deferred entry – making him the first Vulcan to do so (told of this fact, he replied that, as he wasn't truly Vulcan, this statistic was unaffected by his decision) – sarcastically and bitterly giving the chairman the customary Vulcan farewell "Live long, and prosper." ()

When the Enterprise encountered a Romulan Bird-of-Prey that had been attacking Federation outposts, several members of the crew, most notably Lieutenant , expressed prejudiced feelings toward Romulans, growing out of the war between the Federation and the Romulans. When visual contact was made with the Romulan ship and it was discovered that, visually, Vulcans and Romulans looked very much alike, Stiles began expressing strong skepticism and outright hatred towards Spock. His disdain for Spock went so far that Captain Kirk had to reprimand him for his bigotry. ()

As the result of a seventy-year tense political climate between the Federation and the Klingon Empire, many Humans were heavily racist and prejudiced against Klingons in the late-23rd century, including high-ranking Starfleet officers, like Captain Kirk and Admiral Cartwright. ()

In the mirror universe of the mid-23rd century, the Terran Empire was considered racist by Federation standards. ()

The 24th century
When the Cardassians occupied Bajor, they believed themselves to be racially superior to Bajorans since they had much more advanced technology. ()

Racism still existed in the 24th century among some Humans and Vulcans as seen with Lieutenant Commander Christopher Hobson and his attitude toward his commanding officer Data. Hobson felt an android was unfit to be a captain and suggested that certain other species were not "meant" for certain assignments, such as a Klingon being a counselor. () Vulcans who held racist attitudes included Captain , who believed that Vulcan crews were superior to all others in Starfleet, that Vulcans were inherently superior to Humans and other "emotionally handicapped" species, and that Humans made "inefficient" and "unprofessional" officers. ()

Many races held strong racist views against each other, mostly reminiscent of previous hostilities. Klingons and Romulans were generally antagonistic to each other. Most Bajorans were heavily prejudiced towards Cardassians as a consequence of the Occupation. Cardassians often felt the same. Many Federation personnel who fought in the war against them were also heavily racist against Cardassians, including Miles O'Brien. (; )

In the 24th century, photonic lifeforms faced discrimination from organics, making holographic rights an important social issue. ()

As of 2399, the "Romulan Rebirth movement" on Vashti, while claimimg to be striving for the revival of Romulan culture in the aftermath of the Romulan supernova, had strong racist/anti-alien tendencies. ()

Related links
 Civil Rights Movement
 Ethnic conflict
 Ku Klux Klan
 Prejudice
 Race riot
 Xenophobia

External links
 

fr:Racisme
Philosophical movements