Scottish actor Nicol Williamson, perhaps best known for his role as the wizard Merlin in the 1981 film Excalibur, has died aged 75.

His son Luke confirmed last night the actor, once described as being "touched by genius" had died after a two-year battle with oesophageal cancer.

Born in 1936 in Hamilton, South Lanarkshire, Williamson was described as the "greatest actor since Marlon Brando" by playwright John Osborne, and found great acclaim on stage as well as screen.

Williamson made many movies, including one of the Exorcist sequels, but was more praised for his stage work. He was nominated for the prestigious Tony Awards in the US in 1966 for his role in Osborne's Inadmissible Evidence and again in 1974 for Anton Chekhov's Uncle Vanya.

Luke Williamson said his father, survived by his former wife, Jill Townsend, died on December 16 in Amsterdam. He added he had always been "fiercely proud" of his Scottish roots.

Williamson had begun his sometimes tempestuous theatrical career at the Dundee Rep in the 1960s, and last night the theatre said in a statement: "We were saddened to hear of the passing of actor Nicol Williamson. Nicol was enormously talented with a varied and successful career."

The actor, who trained at the Birmingham School of Speech and Drama, had unofficially retired from acting at the end of the 1990s, his last movie being Spawn in 1996.

He had grown dubious of the merits of the acting and movie world and was working on a music project in his final years, his son said.

Luke Williamson told The Herald: "He was fiercely proud to be Scottish, he would quickly correct anyone who would refer to him as English. He was Scottish through-and-through.

"Dad was always surprised when people praised him, he was not the type to brag, and although he knew he was talented, he was never the man to blow his own horn.

"He was a very private man, I don't think anyone knew he was ill, and he was really hoping to come out the other side."

On a statement on his father's website, Mr Williamson added: "He gave it all he had. He never gave up, never complained, maintained his wicked sense of humour to the end. His last words were 'I love you'. I was with him, he was not alone, he was not in pain.

"He leaves behind him an immense body of work – movies, stage performances, music, book narration, poetry and prose."

Although Excalibur, directed by John Boorman, was perhaps his most famous film, it was not his most favourite movie-making experience, his son said.

"He really didn't enjoy making that movie very much, however he was a great lover of history and myth and legend and he gave a great performance – it really was something else," he added.

Williamson drew rave reviews – prompting opinions he was one of the best actors of his generation – for his roles in Hamlet and Uncle Vanya. Prime Minister Harold Wilson praised him to US President Richard Nixon, who invited Williamson to stage a one-man show at the White House.