Han Fiezi and/or Li Si. They are both the leading supporters of Legalism today.
supporter (proponent is a noun).
Shih Huang Ti
is to end or someone that that is againist slavery
A Zhdanovist is a proponent or supporter of Zhdanovism - the political and cultural doctrine of Andrei Zhdanov.
Samuel Gompers was a leading proponent of the formation of labor unions.
Max Weber
yes
Max Weber.
John Dewey
Yes
The definition of the term 'exponent' is a person who supports or advocates. Some synonyms for the word are champion, defender, proponent, protagonist, second, supporter and spokesperson.
Al Gore