Benjamin Lay comes to mind. He was a Quaker in the early to mid 18th century who was quite theatrical in his protests and demonstrations against slavery. While he didn't change the laws in Pennsylvania during his lifetime, the Quakers did eventually follow his lead and excluded slaveholders from their meetings; eighteen years later, slaveholding was abolished in the colony. Considering the amount of work Quakers did in the following century, both as Abolitionists and as Underground Railroad "Conductors," it's arguable that he helped get that (ahmm) train in motion.

Benjamin Lay first encountered the horrors of slavery in Barbados. When he moved to Pennsylvania in the 1730s, he found slavery there as well, and began staging protests against it, as well as boycotts against tobacco and sugar, primarily produced by slave labor. He was chased out of a few places and even disowned by the Quaker establishment of the time, thanks to his love of the Cynic philosophers and his desire to speak bluntly and clearly about the evils he saw men doing. However, his words and work had an effect, and eventually, in 1758, the Quakers began the process of disowning slaveholders.

Marcus Rediker released a well-reviewed book three years ago about this little-known figure in Colonial history, and he also wrote an article for The Smithsonian around the same time.

Marcus Rediker. The Fearless Benjamin Lay: The Quaker Dwarf Who Became the First Revolutionary Abolitionist. Boston : Beacon Press, 2017. 212 pp. $26.95 cloth.