protagonist

The leading character in a drama, story, or narrative; a champion or advocate of a particular cause or idea.

• (related: antagonist /ænˈtæɡənɪst/ n — the opponent)

• main protagonist
• female protagonist
• unlikely protagonist
• protagonist of the story
• protagonist in

1. 1.The novel's protagonist, a young immigrant woman, navigates the complexities of life in 1920s New York. (main character)
2. 2.She emerged as the leading protagonist of the environmental movement in her country. (champion/advocate)

• hero/ˈhɪəroʊ/— the main good character — more specific
• lead/liːd/— the main performer — more informal
• advocate/ˈædvəkeɪt/— a supporter of a cause — for the second meaning

from Greek "protagonistes" (the first actor) — "protos" (first) + "agonistes" (actor, competitor) — the first/leading actor in a Greek play