The rugby league world is in shock following the death of 49-year-old Green at his Brisbane home on Thursday morning, with a post mortem examination to be conducted.
A star in his own right as a player, Green notched 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.
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 Wayne Bennett confirmed on Thursday he was to be offered an assistant role at the Dolphins next year.
Green's family released a statement, saying they were devastated by his death.
"We have lost a devoted husband, loving father and wonderful brother and son.
"We cannot find the words that would come close to expressing our feelings, however we would like to extend our thanks to those who have reached out to us with their love and support.
"Our family is still trying to understand this tragedy and we request space and time as we come to terms with this loss."
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.
Cowboys chairman Lewis Ramsay paid tribute to Green's decorated history with the club and his pivotal impact.
"Paul first came to our club as a player in the late 90s and was the club's first Origin representative, but his lasting legacy emanated from his seven-season tenure as head coach of the North Queensland Cowboys," he said.
"Paul's arrival as head coach transformed our club from finals contenders to an immediate premiership force, culminating in the historic 2015 grand final victory.
"We will forever remember Paul as one of the greatest contributors in Cowboys history."
Michael Morgan, who played five-eighth in the Cowboys' premiership win, said Green was "more than influential" in his career.
"You grow up playing (rugby league), you think you know everything but he just opened up a whole new world to the actual knowledge of the game for me," Morgan told Triple M.
"I've never been able to thank him enough."
Australian Rugby League Commission chairman Peter V'landys said his thoughts were with Green's family and friends.
"I had the pleasure of sitting on the NRL Competition Committee and found Paul to be a passionate, smart and witty individual. Our condolences go to his family and to his many friends," V'Landys said.
The Roosters and Broncos also passed on their condolences to Green's family and said they were deeply saddened to hear of his passing.
Green is survived by wife Amanda and children Emerson and Jed.
