You could get a variety of answers to this question, but I will suggest that three other characters who hide their identities for acceptance are Dill, Miss Stephanie Crawford, and Mrs. Dubose.
Dill tells wild and fanciful stories the entire first summer he is visiting Maycomb, because he doesn't want to admit that his parents basically get rid of him each summer for a break. His imagination and sense of humor likely both grew from a deep loneliness.
Miss Stephanie Crawford is known as a neighborhood gossip and that is about all. Anytime a character is used as a shallow reminder of things that are obvious, it can be assumed that there is more there than meets the eye. Certainly, we'll never know, as Harper Lee didn't take the time to go down that road. But I would suspect that Miss Stephanie spent many years cultivating such a role for herself so that she would at least be something rather than nothing, in Maycomb.
Finally, Mrs. Dubose, a morphine addict, scares the children away by sitting on her front porch cursing everything under the sun. Again, we know this woman has a depth to her that runs deep. Even Atticus respects her. She's a minor character, however, and while her entire story is left untold, we have to assume that the crotchety old woman presented on the porch is not really the person Mrs. Dubose wants to be remembered as.
An interesting idea to think about! It seems to me the character who most has to hide his identity in this story is Arthur Radley. Literally and figuratively, he is forced to hide himself from his community. He is rarely seen, and when he does show himself he appears as anything but a hero who saves someone's life by stabbing someone else. In fact, two of those who are most sworn to uphold the law in Maycomb actually agree to a lie in order to protect him. Boo is a recluse who has been reaching out to the Finch children as a friend.
I also think of Calpurnia, the Finches' black servant who changes her way of speaking when she is with her own people. She learned to read and write from the Bible and law books, so she doesn't speak as most blacks in her community do. When Scout asks her why she speaks differently around them, Calpurnia explains she doesn't want them to think she's putting on airs.
A third character who is forced to be someone they're not is, tragically, Mayella Ewell. We know the family from which seh comes, and we especially see the worst of those characteristics in her father. Mayella is poor and uneducated and presumably cut from the same cloth as her father; however, when we see her on the witness stand we realize she is a lonely young woman whose only hope of a friend is a kind black man who feels sorry for her. She lives in the worst of circumstances, yet she plants flowers where she can. She is forced to cry rape against Tom Robinson, the only man who apparently ever showed her some kindness.
Calpurnia, the cook for the Finch family (and also a mother-figure to the children) is an educated woman whom Atticus trusts to uphold his standards as a parent while he's gone. Cal teaches the children to read and write, and she corrects them when their behavior is out of line. When the children visit Calpurnia's church with her, they notice that she speaks differently to her fellow parishioners than she does in the Finch household. (Essentially, Cal speaks in the southern black dialect in the presence of other blacks at church.) When the kids question her and point out that she used improper grammar when she knew it was wrong, she explains that she speaks that way so that no one accuses her of being "better" than they are because she's educated and well-spoken.
Also, Mayella Ewell is portrayed as a pitiful, lonely, and even caring individual who's stuck in a bad situation. Her father is abusive, she's responsible for taking care of her siblings, and she has no one to keep her company. During the trial, we learn that she made advances toward Tom Robinson--and that her father saw and beat her for it. Because it was socially unacceptable for a white woman to kiss a black man in the time period in which the novel is set, Mayella is forced to lie about her behavior.