Playwright Peter Shaffer, whose durable, award-winning hits included "Equus" and "Amadeus," has died. He was 90.

Shaffer's agent, Rupert Lord, said Shaffer died Monday while on a visit to southwest Ireland with friends and family.

Born in Liverpool in 1926, Shaffer had his first big hit in 1964 with "The Royal Hunt of the Sun," a drama about the Spanish conquest of Peru that was staged by Britain's newly founded National Theatre.

Shaffer went on to write many of his plays for the theater, from where they often moved on to Broadway.

For much of his long career Shaffer achieved the often-elusive goal of combining commercial and critical success, writing literate, cleverly crafted plays that became box-office hits in London and New York.

In 1965, the National Theatre staged Shaffer's farce "Black Comedy" with a cast including Maggie Smith and Derek Jacobi.

His 1973 play "Equus," about a troubled stable boy who inexplicably blinds horses, was filmed in 1977 by director Sidney Lumet with Peter Firth as the boy and Richard Burton as a psychiatrist who tries to help him.

It was revived in 2007 as the stage debut of "Harry Potter" star Daniel Radcliffe.

Shaffer's 1979 play "Amadeus," about the rivalry between Mozart and less-talented composer Salieri, won five Tony Awards in its Broadway run — which starred Ian McKellen as Salieri — and was turned into a 1984 film by Milos Forman that won eight Academy Awards.

The play will be revived this fall at the National Theatre, whose artistic director Rufus Norris called Shaffer "one of the great writers of his generation."

"The plays he leaves behind are an enduring legacy," Norris said.

Shaffer was knighted by Queen Elizabeth II in 2001 and inducted into the American Theater Hall of Fame in 2007.

Lord said Shaffer was "one of the true greats of British Theatre as well as a wonderful friend, wickedly funny man and sparkling raconteur whose lifelong passion for his own art was matched by his love for music, painting and architecture."

Shaffer is survived by his brother Brian, nephews Milo and Mark and nieces Cressida and Claudia. His twin brother Anthony Shaffer, a playwright who wrote the 1970s hit "Sleuth," died in 2001.