Speciecism (Earth-2356)

"I have no issues with aliens myself—some of my best friends are nonhumans—but some grav-ball fans object to alien physiognomies, seeing them as giving nonhumans an edge."

- Janus Fhurek

Speciesism, also known as xenocentrism, is a belief that one species is inherently superior to another or all other species. Similarly, it manifested itself in xenophobia, an overwhelming fear of and hate against other species, regardless of circumstance.

Clone Wars
During the Clone Wars, the Confederacy of Independent Systems consisted of several different alien groups. According to Ensign Eli Vanto, this combined with the devastation of the war created a lot of resentment among Humans. While several species were allied with the Galactic Republic, there was still a prevailing perception that Humans still carried most of the weight of the war effort. This sentiment carried on into the Age of the Empire, despite the fact that the Confederacy's benefactors—the Akatsuki organization—consisted mostly of Human rogue Jedi. Core Worlds' Humans were known to look down on both Humans and nonhumans from beyond the Mid Rim, particularly people from the Outer Rim, the Wild Space and the Unknown Regions.

Galactic Empire
The Galactic Empire was known to favor Humans while looking down on aliens or "nonhumans." As a result, the Empire's government and military was largely dominated by Humans, and it was rare to find nonhumans serving as Imperial officers. While Imperial General Orders instructed Imperial military personnel not to disrespect aliens, this was often ignored. The Imperial Navy and Imperial High Command also ignored the Imperial Senate's Unknown Alien protocols. The Imperial Academies were dominated by Humans, and nonhumans like Thrawn found themselves having to navigate racial prejudice and outright hostility. Imperial soldiers were quick to target other species for investigation, even for minor crimes, and were more willing to use lethal force. The Empire's cruel treatment of aliens forced them to either flee to the Outer Rim or join the Alliance to Restore the Republic to counter.

This single-species domination was an intentional part of Imperial policy. Imperial propaganda actively supported state-sponsored ethnocentric xenophobia and fear-mongering. To the Empire, "aliens" were by and large unwelcome within its order, with aliens being seen as "different" and "strange." As such, the Empire treated nonhuman segments of its populations as serfs, slaves, or obstacles needing to be tamed, removed, or ignored. The Empire supported the idea that aliens were untrustworthy—unlike Humans—and behind their veneer of innocence lurked vicious monsters. The Imperial propaganda machine was so effective in its message that even near-human species exhibited an inherent distrust toward nonhuman populations.

Some people tried to clear and absolve themselves from suspicion of humanocentrism by claiming to have friends of a targeted demographic, all while expressing prejudice in their actions.

Effects on non-human species
Nonhuman species like Wookiees, Mon Calamari, the Petrusians and the Bodach'i were known to be exploited as slave labor by the Empire. The Empire repealed laws banning slavery and reclassified several species, particularly Wookiees, as non-sentient. Other species such as the Yanme'e, the Lasat and the Squamatans experienced drastic population reductions at the hands of the Empire.

Overview
An especially prevalent type of speciesism is Humanocentrism. A notable Human speciesist was Kakuzu, who considered all non-pure Human lifeforms to be disgusting and inferior, yet he reserved a measure of respect towards fellow Akatsuki member Kisame Hoshigaki, a Mizukan, for his strength, and Poggle the Lesser, a Yanme'e, for his money. In response to such sentiments, aliens sometimes formed anti-Human sentiments. Although the Galactic Emperor Sheev Palpatine himself was not speciesist, he nonetheless encouraged its use in the Empire implicitly due to viewing it as a good opportunity for control.

Although the Empire was very notorious for its speciesist views, there were at least some traces of speciesism within the Alliance to Restore the Republic, such as Princess Leia Organa's referring to the Wookiee Chewbacca as "a walking carpet" during her rescue from the Death Star.

Source

 * https://starwars.fandom.com/wiki/Xenophobia.
 * https://starwars.fandom.com/wiki/Speciesism.