The 48-year-old actor starred in director Danny Boyle's original 2002 horror flick 28 Days Later as survivor Jim and is due to serve as executive producer on the first entry in the 28 Years Later trilogy, though producer Andrew Macdonald has revealed Murphy will not be reprising his role for the upcoming flick.
Speaking with Empire magazine, Macdonald said: "We wanted him to be involved and he wanted to be involved. He is not in the first film, but I'm hoping there will be some Jim somewhere along the line.
Cillian Murphy starred in the original 2002 film 28 Days Later, a horror about a zombie apocalypse. (AP PHOTO)
"He's involved at the moment as an executive producer, and I would hope we can work with him in some way in the future in the trilogy."
Speculation about Murphy's on-screen involvement in 28 Years Later began after the trailer depicted a zombie that fans thought looked like the Oppenheimer star, though it was later revealed that art dealer Angus Neill was the zombified character.
Even so, Boyle - who is reuniting with 28 Days Later writer Alex Garland for the upcoming movie - didn't think fans would mistake the walker for Murphy.
The director joked: "I showed my girlfriend the trailer and she said, 'People will think that's Cillian.' I said, 'Don't be silly.'
"I ignored her. So I've eaten a bit of humble pie since."
28 Days Later - which also starred Naomie Harris, Christopher Eccleston and Brendan Gleeson - followed Murphy's Jim as he awakes from a coma only to discover Britain has been plagued by a terrible pandemic known as the Rage Virus, in which those affected turn into murderous zombies.
While the Peaky Blinders actor will not be seen in 28 Years Later, the movie will introduce a host of new survivors as played by Aaron Taylor-Johnson, Jodie Comer, Jack O'Connell and Ralph Fiennes.
In 28 Years Later, Jamie (Taylor-Johnson) and Isla (Comer) leave their tight-knit island community after their 12-year-old son Spike (Alfie Williams) embarks on a coming-of-age journey beyond the safety of the island, forcing the family to come face-to-face with the Rage Virus.
The 2025 movie will mark the beginning of the series' first trilogy - with the second entry 28 Years Later Part II: The Bone Temple due to hit cinemas next year.
Writer Garland explained it felt like the "natural form" of 28 Years Later was a trilogy.
He said: "This is very narratively ambitious. Danny and I understood that.
"We tried to condense it, but its natural form felt like a trilogy."
Boyle added the 28 Years Later movies would be a "wholly different approach" to what had already been seen before in the series with 28 Days Later and 2007 sequel 28 Weeks Later.
The filmmaker said: "It was about what that 28 years gives you."