Some authors on this list died before publishing their final works. But others, such as E.M. Forster, hid their work from public view:
Purposely kept under wraps during his lifetime, E.M. Forster's tale of same-sex love was written in 1913 and kept secret for nearly 60 years. Maurice’s manuscript famously bears the author’s note to himself: “Publishable, but worth it?”
At the link, you can learn about 9 other novels that emerged only after their authors died.