Gambon, who played the Hogwarts headmaster across six of the eight Harry Potter movies, died on 28 September aged 82, his wife and son announced.
“The wonderful thing about Michael is that he wasn’t an actor you talked about acting with,” he said. “His true passion was restoring 19th-century Italian duelling pistols.”
Of Gambon’s approach to acting, Radcliffe added: “He knows he’s at his best when he’s at his most playful. His ability to switch on was second to none.”
Radcliffe, who currently stars in the acclaimed Off-Broadway production of Merrily We Roll Along, said he spoke more about the craft of acting with Uncle Vernon Dursley Richard Griffiths. The two co-starred in the 2007 Broadway revival of Equus in between the filming of the fifth and sixth Harry Potter films.
Radcliffe said he learned a lot from “watching the way Richard approaches theatre”, which he described as “a process of constant and relentless refinement. You’re never done. Your last show should be your best.”
Despite being known for his memorable on-screen roles, Gambon was also a prolific stage actor, beginning his career with Laurence Olivier as one of the original members of the Royal National Theatre.
In her tribute to the late actor, Harry Potter author JK Rowling recalled seeing Gambon in Shakespeare’s King Lear on a school trip, many years before he was cast in the adaptation of her work.
“I’ve just heard the awful news about Michael Gambon. The first time I ever laid eyes on him was in King Lear, in 1982, and if you’d told me then that brilliant actor would appear in anything I’d written, I’d have thought you were insane,” she wrote.
“Michael was a wonderful man in additional to being an outstanding actor, and I absolutely loved working with him, not only on Potter but also The Casual Vacancy. My deepest condolences go to Michael’s family and everyone who loved him.”
Radcliffe also shared a statement following the news, writing: “With the loss of Michael Gambon the world just became considerably less fun. Michael Gambon was one of the most brilliant, effortless actors I’ve ever had the privilege of working with, but despite his immense talent, the thing I will remember most about him is how much fun he had doing his job.
“He was silly, irreverent and hilarious. He loved his job, but never seemed defined by it. He was an incredible story and joke teller and his habit of blurring the lines of fact and fiction when talking to journalists meant that he was also one of the most entertaining people with whom you could ever wish to do a press junket.”