A British-American playwright and film and television writer. He is most notable for writing the play and the screenplay for the film The King's Speech.
Seidler’s paternal grandparents were killed in the Holocaust. Seidler spent his early childhood in London. He grew up in an upper-middle class family. His father Bernard was a fur broker. When his family's apartment in London was bombed during the Blitz in World War II, they relocated to Lingfield in Surrey. As the war continued, his family fled to America, and it was on the boat trip over to the US that Seidler developed a stammer. Seidler subsequently grew up in Long Island, New York. Seidler believes that his stutter might have been a response to the emotional trauma of the war. By the time Seidler was a teenager, he was well aware that his stammering made others uncomfortable, so he often chose to keep quiet. Numerous forms of speech therapy failed him, until, at 16, he had a breakthrough. “I resolved that if I was going to stutter for the rest of my life, people were going to be stuck listening to me. I had been depressed, but now I was angry — I decided I deserved to be heard.
Seidler arrived at Hollywood at the age of 40, and his first job there was writing Tucker: The Man and His Dream for Francis Ford Coppola.
In late 2005 Seidler was diagnosed with throat cancer, but he is currently (2011) in remission.In 2011 Seidler was nominated for an Academy Award for Best Original Screenplay for the film The King's Speech. When writing the script, Seidler discovered that his own uncle, also a stutterer, had been sent to see the speech therapist Lionel Logue.
In February 2011 Seidler won a BAFTA award for Best Original Screenplay.