Because of the lack of innocence in most of society's figures today, one would be hard pressed to find a mockingbird who would live up to Lee's standards. While many people choose to do only good, we often fall short and end up harming someone else unintentionally. Humans who start up non-profit organizations, not for personal recognition, but for the good of others and who believe that they can make a difference might be mockingbirds. They still maintain that optimistic innocence that no matter how many have failed in the past to do what they are attempting, they might be the one who succeeds in helping others while not becoming jaded.
Moreover, I believe that soldiers who enlist to serve their country and to make life better for others in countries that do not enjoy our freedom are mockingbirds. Certainly, not every American soldier meets this high standard, but I have met some. They selflessly risk their lives for the good of their comrads and innocent civilians while not desiring to do any harm. It requires a certain amount of innocence to believe that you can serve in the armed forces and maintain the high standards and personal philosophy which seeks to make the world better for all who are innocent.
I think it would be very difficult to name any public figure as a mockingbird today, because we are constantly surrounded with news of our public figure's wrongdoings (perceived or otherwise). Some might argue that Michael Jackson became a mockingbird, giving the world only amazing music and a legacy as the most charitable celebrity in the Guinness Book of World Records. Others, of course, would argue that he was highly suspicious, and though he was acquitted of child molestation, many people feel that he carried a stigma because of the trials.
The list goes on. It's difficult to pinpoint one person who's good and innocent, and yet persectued. One way we might think about this is in terms of paparazzi. A public figure who is decent, hard-working, and did not necessarily choose to be a public figure, hounded by photographers, could be a modern day Boo, someone who is exposed when they have no desire to be. But again, I think you'd be hard-pressed to find someone in the public eye who didn't make a conscious choice to be there.
Perhaps anyone who goes through life with a gentle and loving spirit, doing good and causing no pain or suffering to others could be considered a mockingbird. Surely there are millions who live their lives this way, but their lives are not noted in the larger society. Their lives are not recognized by those who do not know them; they are not famous or celebrated. This fact, though, does not diminish the value of their lives and their contributions. They, these private mockingbirds, do not seek praise, either. They just do what they do because they are generous and unselfish. Knowing such people in our own lives is a blessing.
Sometimes private mockingbirds do become public figures. I think of Mother Teresa, toiling for years in obscurity to relieve suffering and comfort the poor. Her deeds and her dedication are now very well known, and she is revered by the world at large for her personal and unselfish mission.
I'm thinking if you mean someone in mass media, Taylor Swift, Jennifer Lawrence, Bono, and Angelina Jolie would be good examples because these celebrities are critiqued and criticized based on their abilities, but we don't see them as real people anymore at times. Miss Maudie says in the novel that killing mockingbirds is a sin because all they do is make music for us, and this is true of many celebrities. If they are providing entertainment for us and kindness around the world, aren't we being sinful by shaming them based on the very abilities they use to entertain us? Aren't we killing mockingbirds?
In the the novel To Kill a Mockingbird, only one character is specifically compared to a Mockingbird. This character is Boo Radley. When Atticus insists on reporting the accidental killing of Bob Ewell by Boo Radley, Scout says,
Well. It'd be sort of like shootin' a mokingbird, wouldn't it?
Meaning that Boo Radley, like a Mockingbird, did not cause any harm to any one, and it making him defend the charge of purposely killing Bob Ewell would be like killing a mockingbird, which is forbidden as per their culture.
I am sure, In today's as in society of any other time there are many people like mockingbird in the sense that they provide only good things and do not harm anyone.