Students have been warned not to dress up as "chavs or Tories" or wear sombreros under new guidelines seen by the BBC.
Kent Union, which represents students from the University of Kent, said outfits which threaten others' rights to "a safe space" should not be worn.
Banned costumes include cowboys, Native Americans, priests and Mexicans.
The union said the draft guidelines were in response to "complaints" in recent years.
In the guidance, which has been circulated to student groups, the union says it will not tolerate behaviours that seek to offend a "particular race or culture".
Students are warned against using props, such as maracas, to "emphasise racial stereotypes".
They are also told not dress as "any influential black person with black face paint (black face)".
Also on the banned list are costumes which centre around historical events that "degrade someone's ancestry in a derogatory way", such as "the Crusades, Nazi uniform, ISIS bomber and The Prophet Mohammed (peace be upon him)".
According to the union, acceptable costume choices include cartoon characters, letters of the alphabet, cave people and aliens.
In a statement, Matt Goodwin from Kent Union said the fancy dress policy was "a draft proposal".
He added: "We will be consulting with our executive groups to gain further feedback.
"We of course want students to enjoy themselves and often host fancy dress parties in our own nightclub, but we would ask students to be mindful of their choices and whether any offence could be caused."