Green is reported to have died in his Brisbane home on Thursday morning, with a post mortem examination to be conducted.
A star in his own right as a player, Green played 162 games across five different clubs as a halfback, five-eighth and hooker while also playing seven State of Origins for Queensland.
Green also won the 1995 Rothmans Medal as the league's best and fairest player that year.
But he will forever be remembered as the man who helped guide North Queensland to their maiden premiership in 2015.
In total, he was in charge of the Cowboys in 167 games with the 2015 title coming in just his second season as head coach.
He left the club in 2020 and took over as Queensland's State of Origin coach last year.
When he resigned from that job last September, it appeared certain he would resume his days as an NRL coach.
He was linked to Wests Tigers at the end of last season and was expected to take on a role at the Dolphins next year.
Green's death will hit the NRL hard.
Beyond those still at North Queensland, he has coached several players across the game who began their careers in Townsville or played for the Maroons last year.
On Thursday night alone Cameron Munster, Xavier Coates and Viliame Kikau were among those due to take to the field just hours after learning of their former coach's death.
Green was in Sydney only last weekend for the Cronulla ex-players' reunion, a club where he played 95 games before moving north to the Cowboys.
He was also a part of the Sydney Roosters' 2002 premiership-winning squad, before finishing his playing days at Parramatta and Brisbane.
"We are deeply saddened at the tragic passing of Queenslander and former Bronco, Paul Green," the Broncos tweeted.
"A legend on and off the field gone far too soon."
Green is survived by wife Amanda and children Emerson and Jed.
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