What are examples of characters and their secrets in Charlotte Bronte's Jane Eyre?

Jane Eyre is a book full of secrets. Mrs. Rochester is without question the biggest one, but many characters have secrets, or are involved in deceptions of one sort  or another. Here are some, other than Bertha:

Mrs. Reed receives a letter from Jane's rich uncle asking about Jane's whereabouts, which she doesn't tell Jane about until her conscience gets the better of her at the very end of her life. Another kind of secret that she is "keeping" from her deceased husband is her treatment of Jane. Jane calls her out on this: “My Uncle Reed is in heaven, and can see all you do and think; and so can papa and mama: they know how you shut me up all day long, and how you wish me dead.” Young Jane's ability to see through Mrs Reed is quite shocking!

Jane adopts a false identity after she leaves Thornfield, telling everyone that her name is Jane Elliot. St. John discovers her real name when he notices that she has absent-mindedly written "Jane Eyre" in the margin of a drawing.

Diane, Mary and St. John are secretly Jane's cousins, a fact that Jane learns only after St. John uncovers her true identity.

Rochester pretends to be a fortune teller and tells the fortunes of his guests, including Blanche and Jane. Everyone is fooled except for Jane; when Rochester reveals himself to her, she is, or pretends to be, angry: “I believe you have been trying to draw me out— or in; you have been talking nonsense to make me talk nonsense. It is scarcely fair, sir.”

Mr. Mason's secret is that he is Bertha's brother -- his sudden appearance causes Rochester to go "whiter than ashes."

Then, of course, there are secrets that are not revealed in the text, the missing parts of the story, like Bertha's history, or who Grace Poole might really be, or Rochester's relationship with his father and brother. These "negative spaces" in the story shape the meaning as much as the actual narrative itself. If you pay attention to the secrets in the novel, you begin to see a pattern of truth and falsehood that marks all the characters, and which resolves itself into Jane's final union with Rochester, a marriage in which, at last, there are no secrets.