The family of To Kill A Mockingbird author Harper Lee, who has died aged 89, has said she was a "generous soul" and that they will "miss her dearly".
A statement from the family confirmed she had died in her sleep on Friday morning.
It 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 awarded the Pulitzer Prize in 1961 for To Kill A Mockingbird and it remained her only book until 2015.
Set in the Deep South in America during the 1930s, it details the life of tomboy Scout, real name Jean Louise Finch, and the events that unfold when her father, Atticus Finch, a Maycomb lawyer, is assigned to defend a black man on a rape charge.
Born Nelle Harper Lee in 1926, she grew up in Monroeville, Alabama and 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.
To Kill A Mockingbird went on to become a classic and Lee was also awarded the Presidential Medal of Freedom.
Lee was fiercely private and following the success of her book she rarely granted interviews.
Last year she released a statement announcing she would be publishing a follow-up for To Kill A Mockingbird, titled Go Set A Watchman.
The book featured her beloved Mockingbird characters, with the main protagonist, Jean Louise Finch, now an adult.
The book 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 Lee, then 88, 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.
Fellow authors and figures from the world of entertainment paid tribute to her on social media.
Lee's literary agent Andrew Nurnberg said knowing the author had been "not just an utter delight but an extraordinary privilege".
He said: "When I saw her just six weeks ago, she was full of life, her mind and mischievous wit as sharp as ever.
"She was quoting Thomas More and setting me straight on Tudor history. We have lost a great writer, a great friend and a beacon of integrity."
Tom Weldon, chief executive of Penguin Random House UK, said: "We are honoured to have been Harper Lee's publisher and so saddened to hear of her passing.
"She was an extraordinary writer and readers around the world will always be thankful for her legacy."
The president and publisher of HarperCollins US general books group and Canada, Michael Morrison, said: "The world knows Harper Lee was a brilliant writer but what many don't know is that she was an extraordinary woman of great joyfulness, humility and kindness."
He added: "She lived her life the way she wanted to - in private - surrounded by books and the people who loved her. I will always cherish the time I spent with her."
Man And Boy author Tony Parsons paid his respects on Twitter: "Harper Lee said more in one book than most of us manage in a lifetime."
Hollywood actress Reese Witherspoon narrated the audiobook of Go Set A Watchman and paid tribute on her Instagram account.
Alongside a picture of Lee, she wrote she felt incredibly lucky to have "had the opportunity to read and give voice to Harper Lee's brilliant words".
She went on: "Her perspective helped me, as a young reader and Southern woman, understand the place that I grew up in, with all its glory and its flaws. Her romantic view of the South - with all its open charm and warmth - never shielded us from the divisive attitudes running rampant through our beloved society."
She ended her message writing: "She revealed it all...the glory and the fear and the hate and the beauty. May she rest in peace. #HarperLee #RIP"