Sir Peter Shaffer, the celebrated writer of Equus and Amadeus, has died at the age of 90 after a short illness.
The renowned playwright died at the Marymount Hospice in Ireland, with family by his side, his agent said.
A statement from Macnaughton Lord Representation said: "It is with great sorrow that we must announce the death of our friend and client, Sir Peter Shaffer CBE whilst on a visit to Ireland with friends and family.
"He was 90."
Sir Peter "passed away peacefully" at 5:30am on June 6 at the hospice in County Cork with his niece Cressida at his side.
The statement continued: "His great friend and American agent, Dennis Aspland remained with him in Ireland throughout his short illness.
"He had been struggling with his health for some time, but was both determined and delighted to have been able to celebrate his 90th birthday in Ireland last month with close family and friends."
Respected as "one of the true greats of British theatre", Sir Peter wrote more than 18 plays.
Equus and Amadeus, the two works for which he remains best known, won the Tony Award for best play in 1975 and 1981 respectively.
Both were adapted for the big screen, with Amadeus winning eight Academy Awards at the Los Angeles ceremony in 1985.
Harry Potter star Daniel Radcliffe starred in the London (2007) and New York (2008) productions of Equus.
Sir Peter's other plays include Black Comedy, Lettice And Lovage, The Royal Hunt Of The Sun and Five Finger Exercise.
Much of his working life was linked to the National Theatre, for which several of his plays were written and first produced.
Rufus Norris, director of the National Theatre, said: "Peter Shaffer was one of the great writers of his generation and the National Theatre was enormously lucky to have had such a fruitful and creative relationship with him.
"The plays he leaves behind are an enduring legacy."
A statement on the National Theatre website said: "It is with great sadness that we learn of the death of Sir Peter Shaffer, CBE.
"He was an extraordinary writer, closely associated with the National Theatre."
The theatre added that Amadeus will return to the Olivier stage in the first National Theatre revival since its 1979 premiere.
Sir Peter, who was nominated for numerous awards over the course of his long career, was awarded the CBE in 1987 and knighted in 2001.
He lived in New York for a number of years, but loved to visit London and Ballymaloe House in County Cork "in particular".
His agent said the internationally respected writer "is survived by his brother, Brian, nephews Milo and Mark and nieces Cressida and Claudia, whose father and Peter's twin, the playwright and screenwriter, Anthony Shaffer, died in 2001.
"We shall all miss him terribly," he said.
A private funeral will take place in London "shortly" and details of a memorial service will be announced in due course.