A role model can be defined as "a good example to follow," but people will not all agree on what constitutes a "good example." At some point, many of the children who want to be policemen, astronauts, and their parents eventually look more at musicians, athletes, and actors as their role models. A quick review of the news for any given week will testify to the fact that many of these people are not positive role models.
All of us must decide for ourselves who we find worthy of emulation and what qualities are worth striving for in our own lives. You labeled your question as a literature topic, so here are three admirable qualities of a role model found in familiar literary characters.
The first quality worth emulating is integrity. This is the willingness to stand for what is right, even in the face of persecution or defiance, and Atticus Finch in Harper Lee's To Kill a Mockingbird is a perfect example of this attribute. In a town where a black man who is accused of rape by a white woman is automatically guilty, Atticus examines the evidence and knows his client is innocent. Despite the pressures surrounding him, including physical violence aimed at his children, Atticus maintains his belief that justice must prevail and he works hard to free Tom Robinson. The highest praise Atticus receives come from Miss Maudie, who says "Atticus Finch is the same in his house as he is on the public streets." That is integrity.
The second quality of an effective role model is the willingness to sacrifice oneself for a worthy cause. This characteristic is the one we most admire about firemen, policemen, soldiers, and others who daily risk their lives to keep others safe and free. In literature, Sidney Carton from A Tale of Two Cities, by Charles Dickens, is such a character. Though he lives a rather "wasted life" for too long, when he finds love he is willing to sacrifice everything for it. While sacrifice does not always require the giving up of a life, the willingness to put others above self when necessary is an admirable quality worth emulating.
Finally, accepting responsibility for mistakes is a praiseworthy attribute. It is easy to place blame and point fingers to escape the consequences of our actions, and we start doing that even as little children. When a person is able to admit his wrongs and accept the ramifications of his actions, he is setting a positive example. In The Crucible, by Arthur Miller, John Proctor makes several egregious errors, including having an affair with a young woman. It is true that this is something he does not want to admit publicly in Salem, for adultery was a sin punishable by death. When it becomes clear to him that he must tell the truth and lose his life or allow innocent people to die, Proctor tells the truth. It costs him his life, but he dies with a clean conscience and a pure heart. He accepted the consequences of his actions.
In today's world, role models are too often chosen based on what they wear, how much money they have, or worse. Instead of selecting mere trendsetters as the people we wish to emulate, we should choose the qualities that matter to us and look for people who demonstrate them with consistency. Rather than looking to famous--or infamous--characters, we should look to the people close to us, or perhaps to literary characters who demonstrate those qualities.