This is a great question. There are only a few people in To Kill a Mockingbird who will risk breaking the norms of society. The most obvious person is Atticus. He is the person who embodies courage more than anyone else in the book.
Right from the beginning of the Tom Robinson trial, Atticus knows that he is going to lose. He also knows that his family will be put through hardships on account of his defending Tom Robinson. Even though he knows that these things will take place, he will try his best.
He believes so deeply that this is the right course of action that he will even risk his life. This comes out at the jail. Atticus risks his life in front of a mob.
Here is a telling quote about Atticus's courage:
“Because I could never ask you to mind me again. Scout, simply by the nature of the work, every lawyer gets at least one case in his lifetime that affects him personally. This one’s mine, I guess. You might hear some ugly talk about it at school, but do one thing for me if you will: you just hold your head high and keep those fists down. No matter what anybody says to you, don’t you let ‘em get your goat. Try fighting with your head for a change... it’s a good one, even if it does resist learning.”
Apart from Atticus, there are others who will go against the norms of society. They are people like Miss Maudie, Heck Tate, and Judge Taylor.