Other forms: peacemakers
A peacemaker is a person who helps others solve a conflict and reach a peaceful solution. Of course Gandhi was a famous peacemaker, but even the volunteer on playground patrol can act as a peacemaker too.
An individual can be a peacemaker, and there are also organizations that work as peacemakers. If two countries are engaged in a long war, for example, peacemakers might help negotiate a truce. Diplomats and mediators are peacemakers, and if you help your angry sisters come to a peaceable agreement about whose turn it is to take out the trash, you're a peacemaker too.