Who in The Crucible uses their power in a positive way?

Mr. Hale eventually uses his power in a positive way.  It takes him a while to come around to the idea that the court in Salem is corrupt and that the girls are not being truthful, but once he does realize this in Act III, he tries to step in.  Hale tries to stick up for the Proctors when Elizabeth tells a lie to protect John after he'd sworn that she would never lie.  When Mary Warren accuses John of witchcraft, Hale argues that "this child's gone wild!" and he "denounce[s] these proceedings" by the end of the act.    

By Act IV, Hale has returned to Salem to try to convince those who are about to be hanged for witchcraft, John Proctor included, to confess so that they will not lose their lives.  He insists that Danforth "must pardon them," though Danforth will not because others have already been put to death for the same crimes.  Hale tells Elizabeth, "cleave to no faith when faith brings blood.  It is mistaken law that leads you to sacrifice.  Life, woman, life is God's most precious gift; no principle, however glorious, may justify the taking of it."  Although Hale is, ultimately, unsuccessful at saving anyone from death, he does try, and he's one of the only -- if not the only -- person who actually uses their power to try to do good.  Danforth, Hathorne, Parris, Putnam: they're all corrupt in their own ways.