A Protagonist

1. (authorship) The main character, or one of the main characters, in any story, such as a literary work or drama.Antonym: antagonist
2. A leading person in a contest; a principal performer.
3. (proscribed) An advocate or champion of a cause or course of action.

Usage notes

The use of protagonist to mean a proponent or supporter of a cause is a 20th century development that may have been influenced by the misunderstanding that the first syllable of the word is the prefix pro-, meaning favouring.^[1] This usage is widely considered to be erroneous.^[2][3]