Sir Michael Gambon revealed he was suffering from a health struggle before his passing at the age of 82.
His family issued a statement that revealed the Harry Potter actor died following a "bout of pneumonia".
"We are devastated to announce the loss of Sir Michael Gambon. Beloved husband and father, Michael died peacefully in hospital with his wife Anne and son Fergus at his bedside, following a bout of pneumonia. Michael was 82," the statement read. "We ask that you respect our privacy at this painful time and thank you for your messages of support and love."
Sir Michael revealed in 2015 that he was suffering with a progressive disease that caused memory loss, saying he was forced to give up his stage career as he was struggling to remember his lines.
"Now I can’t really do theatre," he said. "It breaks my heart, but I can’t really remember lines."
However, the star was able to continue working in the film and TV industry using an earpiece so he could be told lines.
In 2019, Sir Michael was forced to pull out of the TV show Breeders, after struggling to remember his scripts.
"Michael is an incredible actor, and was extremely popular on set," a source told The Sun at the time. "But age appears to have caught up with him and he was struggling with the script.
"Lines weren’t going in and sticking as they normally would."
The actor began his career on the stage in the early '60s and later moved to TV and film.
Harry Potter stars share tributes for Sir Michael
Daniel Radcliffe, who starred alongside Sir Michael in the Harry Potter series, shared a tribute to his friend, telling Entertainment Weekly, "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."
"The sixth film was where I got to spend the most time working with Michael," Daniel continued. "He made the hours spent in front of a green screen together more memorable and joyous than they had any right to be. I'm so sad to hear he has passed, but I am so grateful for the fact that I am one of the lucky people who got to work with him."
Emma Watson took to her Instagram Stories to share her own tribute to Michael, writing, "You never took it too seriously but somehow delivered the most serious moments with all the gravitas. Thank you for showing us what it looks like to wear greatness lightly. We will miss you."
Jason Isaacs, who played Lucius Malfoy in the series, took to X to share his tribute, which read: "I learned what acting could be from Michael in The Singing Detective – complex, vulnerable and utterly human. The greatest thrill of being in the Potter films was that he knew my name and shared his fearless, filthy sense of fun with me."
James Phelps, who starred as Fred Weasley, described Michael as "a legend", both on and off camera.
He recalled a moment when the Dumbledore actor helped him with another role on the set, "One day we were shooting Dumbledore's final clock tower scene, obviously quite an intense scene. In between set ups Michael asked what I was up to that weekend. As it happened my brother and I were reading Peter and the Wolf with the Manchester Halle orchestra."
James adds that Michael helped him during his spare time to give him notes, "So we spent what should have been his downtime going over my weekend gig. It is a memory I've always had as one of the highlights of my HP days."
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