Atticus Finch is one of the main characters in Harper Lee's novel To Kill a Mockingbird. It is through his actions that his children, Jem and Scout, come to understand the harsh realities in life. Through his actions, his children come to understand prejudice, hatred, standing up for one's self, and standing up against others (even when the person is considered the minority).
That said, Atticus shows courage in a few different ways. First, he agrees to take on Tom Robinson's case, even though he is a black man and the town is very racist. Second, Atticus takes on the individuals of the town who are racist (as seen in the mob scene outside of the jail). Lastly, Atticus shoots down the rabid dog in the middle. All of theses things speak to Atticus' courage.