martyr
n//ˈmɐːtə(ɹ)//martyr
One who willingly accepts being put to death or willingly accepts challenging and exposing iniquity done to oneself for adhering openly to one's religious beliefs; notably, saints canonized after red martyrdom.
(by extension) One who sacrifices their life, station, or something of great personal value, for the sake of principle or to sustain a cause.
(with a prepositional phrase of cause) One who suffers greatly and/or constantly, even involuntarily.