The end of Season Six was this past weekend.

Robert Carlyle's character got to stop one of the bad guys, using lethal force.

The savior/hero realized that sacrifice, not lethal force, was indicated in her final battle; so she did the sacrificial thing, and was resurrected by a kiss from her son.

And, with six-year contracts having expired, several lead actors decided not to renew; so their characters are off to the Land of Happy Endings, which does not exist on this show!
The character's actor has to leave the show to get there.

The savior is one of those characters.
However, Robert Carlyle is coming back in autumn for season seven, along with Lana Parilla and Colin O'Donoghue. Three of the shades-of-grey troublemaker-characters. While at least three of the "good guys" leave the series.