Born in Dublin, Deasy's credits include the miniseries Looking After Jo Jo, Real Men, England Expects and the final miniseries of Prime Suspect.
There's a report by Jason Deans in The Guardian containing tributes to Deasy.
[Actor Dougray Scott said]: "He was quite simply the most extraordinary and brilliant writer I have ever worked with and one of the most extraordinary and beautiful men I was blessed to have met. Whenever I spent time or talked with Frank I always felt the warmth, wisdom and sheer joy of life that I remember getting from my own father. That's how special he was to me."Deasy wrote about his liver cancer in The Observer last Sunday.
Obituaries to follow.
Update: Tributes on the RTÉ website.
Jane Gogan, Commissioning Editor for Drama, RTÉ Television, said: "Frank Deasy was a writer for television and film who brought a tremendous honesty and passionate intensity to his work. Professionally Frank was coming into his own, working on a range of projects that were all major subjects: the 'Medicis' with BBC, a film project with Ridley Scott based on Philip K Dick's 'The Man in the High Castle' and, closest to his heart, was 'Gaza', a film that will star Helen Mirren. He was also preparing to start on a project for RTÉ following a family across 100 years.Update: More from BBC News and The Scotsman. Tributes on Twitter.
Update: Obituary by Ronald Bergan in The Guardian.
The Passion, the gospel according to Deasy, which the BBC screened at Easter 2008, seemed in contrast to his other work, except for the strong human values. "What I personally was fascinated by was the duality of Jesus in his divinity and his humanity," Deasy told Christian Today. "This is essentially a mystery, but his humanity has to be total, otherwise he is somewhat of a tourist in his own Passion. I've tried to find a human truth that feels real and that is not always the same as a theological truth, and so I would hope that people would be open to the fact they are watching a piece of drama rather than a theological treatise."