LONDON, June 6 (UPI) -- Peter Shaffer, the critically aclaimed playwright known for his successes in both London and on Broadway, has died at age 90.
His greatest successes included Equus, Amadeus and The Royal Hunt of the Sun.
Shaffer's agent, Rubert Lord, said "He was simply at the end of his life but delighted to have been able to celebrate his 90th birthday with friends and then, I think, decided it was time," The Guardian reported.
Shaffer was visiting Ireland when he died. His niece, Cressida Shaffer, was by his side, BBC reported.
Other Shaffer plays included Black Comedy, Lettice and Lovage and Five Finger Exercise.
The National Theatre, which was already planning a revival of Amadeus and presented the world premieres of much of Shaffer's work, described him as "an extraordinary writer."
National Theatre Director Rufus Norris said 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."
Amadeus, a hugely successful psychological drama about the relationship between Mozart and his less gifted admirer and rival composer Salieri, won eight Oscars in 1985, including best film and a screenwriting award for Shaffer. It re-opened in 2004 at the Chichester Festival theatre, a venue also closely associated with Shaffer's work.