James Gunn felt John Cena was an "untapped acting resource".
'Peacemaker' producer Peter Safran has claimed the show's creator Gunn was confident 44-year-old pro wrestler Cena - who played the titular character in 2021 movie 'The Suicide Squad' - would be able to "go deeper" as an actor by bringing superhero Christopher Smith/ Peacemaker from the big to the small screen for the HBO Max series.
Safran told SFX magazine: "I knew that James wanted to tell that story and that he wanted to really go deep with John on that character.
"And when you watch the series, you realise that his dad was every bit as bad as Bloodsport's was - and in some ways, much worse. That was just a tiny little Easter egg in there, and it all gets unpacked in the series.
"I think he felt with John there was a real untapped acting resource there, and that people will be very surprised to see how deep John can go.
"We knew that he could go there, and there's a real pleasure in bringing that to a wider audience."
Safran also revealed HBO bosses didn't instruct the 'Peacemaker' team to change much about the episodes before they were given the green light, and he believes that is down to Gunn penning all eight episodes himself.
He added: "We would hand in each episode and literally [executives] would call him to say, 'Guys, we just really liked it.' There were not a lot of notes - which I think is unusual, because the quality of the HBO shows in the past is so incredibly high.
"James knew the show that he wanted to make, and because he was writing all eight episodes, it was just all from the brain of James Gunn."