The writer, best known for productions Equus and Amadeus, passed away on Monday (06Jun16) at a hospice in Ireland, aged 90.

He wrote the drama, about a teenage boy with a disturbed obsession with horses, in 1973 and Harry Potter star Daniel took the lead role of Alan Strang in a West End revival in 2007 and its subsequent Broadway transfer in 2008.

The actor took social media site Google+ to praise the playwright for his work, and to recall how Equus affected his acting career.

"Peter Shaffer was and remains one of the U.K's greatest playwrights," he writes. "He created challenging, moving and fantastically theatrical work and was also an incredibly kind, generous and funny man.

"In my career Equus remains one of the most important and valuable things I've ever done in terms of how much I learnt from it. I will forever be grateful to him for trusting me to play the character of Alan Strang at a time when I had extremely limited experience on stage. I feel very privileged to have worked with him and will miss him."

Daniel wasn't the only star to mourn Shaffer on social media - Alec Baldwin shared a link to an article about his death and wrote, "Sad... Another terrible loss."

British actor/theatre director Simon Callow, who previously starred in a production of Amadeus, told BBC Radio 4 on Monday (06Jun16), "He was so alive, companionable, the wittiest of the men, the most charming and hilarious of raconteur, I wept with laughter sitting around tables with Peter... (he was) utterly, utterly in love with the theatre, as he had been from a boy."