Harper Lee, the celebrated author of To Kill a Mockingbird, has died at the age of 89.
Her family confirmed the news and said she was a "generous soul" and that they will "miss her dearly".
Rest in peace, Harper Lee. https://t.co/JpxHoAXBPZ— Penguin Random House (@penguinrandom) February 19, 2016
She died in her sleep this morning.
Her family said: "Her passing was unexpected. She remained in good basic health until her passing. The family is in mourning and there will be a private funeral service in the upcoming days, as she had requested. Ms Lee was 89."
Her oldest nephew and the family spokesman, Hank Conner, said: "This is a sad day for our family. America and the world knew Harper Lee as one of the last century's most beloved authors. We knew her as Nelle Harper Lee, a loving member of our family, a devoted friend to the many good people who touched her life, and a generous soul in our community and our state. We will miss her dearly."
Lee was born Nelle Harper Lee on 28 April 1926 in Monroeville, Alabama. She was the youngest of four children.
Her father, Amasa Coleman Lee, was a lawyer and it is reported that her character of Atticus Finch was loosely based on him.
She released the famous book on the racial troubles of the American deep south in 1960 and later won a Pulitzer Prize.
To Kill A Mockingbird went on to become a classic and she was also awarded the Presidential Medal of Freedom.
She was famously very private and rarely made public appearances.
After more than 50 years, the writer published her sequel to the book, Go Set a Watchman, in July last year.
The book featured her beloved Mockingbird characters, with the main protagonist, Jean Louise Finch, now an adult.
The long-awaited follow-up sold more than 105,000 copies on its first day.
Lee suffered a stroke in 2007 and with the release of her book last year, concerns were raised about the extent of her involvement in the project.
At the time, her agent was forced to respond to reports suggesting the 88-year-old was being taken advantage of over the publication of the book.
Authorities in her native Alabama closed their investigation into the issue, saying the reclusive writer had "made it quite clear" she wanted the book published.
Rest in peace, Harper Lee. "The one thing that doesn't abide by majority rule is a person's conscience."— Tim Cook (@tim_cook) February 19, 2016