Teenager Joel Dark has died in hospital, five days after collapsing following a head injury in his Newcastle first-grade rugby league debut.
The cousin of NSW and Australian captain Boyd Cordner had been in a critical condition in John Hunter Hospital, where he underwent surgery.
The family of the 19-year-old has requested that their privacy be respected and expressed their gratitude to the Central Newcastle Rugby League Football Club, hospital staff and all those who have assisted and supported the family.
The Newcastle Rugby League has postponed all fixtures for this weekend out of respect for Dark and his family.
The Newcastle Knights and Cordner's Roosters will pay tribute to Dark at their Saturday NRL match given his links to both clubs.
A minute's silence will be observed before the game at the SCG, with players to wear black armbands and both clubs offering their condolences on Friday.
"The Dark family have many friends throughout our team and town, and we are standing alongside them today mourning this unimaginable loss," former Knights player-turned general manager Danny Buderus said.
"I know the family will get all the support they need from the tight-knit community of Old Bar in the days and weeks ahead, along with the entire game as we unite in this tragic loss."