Han Fiezi and/or Li Si. They are both the leading supporters of Legalism today.
Han Fei Tzu
supporter (proponent is a noun).
Shih Huang Ti
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
Max Weber.
yes
John Dewey
Yes
B.F. Skinner was a leading proponent of behaviorism in the United States until his death in 1990. Skinner's work focused on the principles of operant conditioning and reinforcement, which had a significant influence on psychology and behaviorist theory.
Al Gore
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.