assertor

noun

1. One who asserts or avers.

   “[N]o waver in Judgment, have I, though Gods mercy, ever been; but a conſtant aſſertor of, and ſufferer for my ſatisfiedneſs in, and adheſion to, the piety and probity of my breeding and belief, vvhich vvas ever, yet is, and I hope, through Gods grace, to death ſhall be, in point of Religion according to the Doctrine and Diſcipline of the Church of England.”

2. One who supports, affirms, defends, or vindicates; a champion.

   “[I]t is a deed of higheſt charitie to help undeceive the people, and a vvork vvorthieſt your autoritie, in all things els authors, aſſertors and novv recoverers of our libertie, to deliver us, the only people of all Proteſtants left ſtill undeliverd, from the oppreſſions of a Simonious decimating clergie; […]”