J.J. Murphy died on Friday, Aug. 8, at the age of 86, just four days after filming his first scenes for the highly anticipated upcoming Season 5 of HBO's hit fantasy drama series "Game of Thrones."

"I am heartbroken to pass on the news that the wonderful J.J. Murphy passed away this morning, Aug. 8, 2014," Murphy's agent said in a statement to E! News. "I had the pleasure and honor to be his Agent for the last 18 months and have never encountered a man with more spirit, passion and love for his craft. At this time, our thoughts are with his family."

The Belfast Telegraph first reported the Irish actor's unfortunate death after collapsing. His character was set to make debut on George R.R. Martin's series, as Murphy took the role of Ser Denys Mallister, a knight of House Mallister and a member of the Night's Watch, at the end of last month. Mallister commanded the Shadow Tower for 33 years and was a leading candidate to become the next Lord Commander.

Executive producers D.B. Weiss and David Benioff took to the official "Game of Thrones" Twitter account on Monday to announce that Murphy's role will not be recast for the forthcoming season: "Official statement from the creators of @GameofThrones: 'We will not be recasting J.J. Murphy. He was a lovely man, and the best Denys Mallister we could have hoped for. And now his watch is ended.' - D.B. Weiss and David Benioff."

J.J. Murphy's funeral will be held in Belfast on Wednesday, Aug. 13.

"Game of Thrones" Season 5 will have nine new cast members, including Toby Sebastian as Trystane Martell, Keisha Castle-Hughes as Obara Sand and Jonathan Pryce as the High Sparrow.