Some never apologize for what they say/do. Have you ever apologized to anyone for someone else's insult/attack/rudeness? Why?

I realize it is a second-hand apology. I realize that the ONLY significant apology should come from the miscreant, not me but I've done it more than once just to let the harmed person know that someone noticed and cared enough to say something.   What about you? Ever do it?