1) Advocate 2) Advocator 3) Exponent 4) Proponent 5) Sad case is 22, bigot 
[n] - a person who advocates the supremacy of some particular group over all others
supremacist 1. Someone who takes supreme authority for him/herself. 2. Someone who believes in the supremacy of one race, sex, or social group.
noun a person who advocates the supremacy of some particular group or race over all others
a person who believes in or advocates the supremacy of a particular group, esp. a racial group: a white supremacist.