This Unnamed Nun was an accomplice of Red John. She appeared in the church as Patrick Jane was about to kill Thomas McAllister aka Red John. She started approaching Jane under the guise of trying to talk him out of killing McAllister. She continues approaching Jane preaching that violence is "not the answer". When she is close enough she pulls out a knife and tries to kill Jane, only for Jane to knock her out while McAllister escapes.
McAllister's Nun whilst trying to stab Jane
Red John Accomplices