Benjamin Lay is not to be overlooked.
One Sunday, 18th-century Quakers living in Abington, Pennsylvania, near Philadelphia, were met with a strange sight outside their morning meeting. The snow lay thick on the ground and there was Benjamin Lay, a member of the congregation, wearing little clothing, with his “right leg and foot uncovered,” almost knee-deep in the snow. When one Quaker after the next told him that he would get sick or that he should get inside and cover up, he turned to them. “Ah,” he said, “you pretend compassion for me, but you do not feel for the poor slaves in your fields, who go all winter half-clad.”
Source: The 18th-Century Quaker Dwarf Who Challenged Slavery, Meat-Eating, and Racism