I would also like to advocate for Thomas Paine, who in addition to writing Common Sense and The Rights of Man (instrumental in the American and French Revolutions) published the first prominent piece in the American colonies advocating for the abolition of slavery in Pennsylvania Magazine. (Historians don't believe he wrote it, as it didn't contain a byline, but he did run it.)

This is a great, list, btw, including a couple fresh names for me. Thank you!