North Queensland utility Te Maire Martin has announced his immediate retirement from rugby league, unable to be cleared by doctors for a bleed on the brain.
The 24-year-old has been sidelined since April last year after complaining of migraines.
Although he has made some developments in his recovery, the Cowboys announced on Sunday night that his once-promising NRL career is now over.
"The last nine months have been extremely difficult," Martin said in a statement.
"I'd like to reassure everyone that I'm doing well and I have recovered to the point where my day to day life isn't affected, but I can't get past the contact stage of training, which means I can't play footy anymore.
"I'd like to thank the Cowboys for their unwavering support - they could not have done any more for me, particularly the medical staff - as well as the club's members and fans for their well wishes."
Martin made his NRL debut with Penrith in 2016, scoring a try and kicking the match-winning field goal in his first NRL game.
He was then signed by the Cowboys where he has spent the past three seasons playing five-eighth, fullback or a utility option from the bench.
In addition to his 55 NRL matches, Martin represented New Zealand in four Kiwis internationals.
"We'd like to thank Te Maire for everything he's done for the club, said Peter Parr, Cowboys director of football.
"He's been a wonderful contributor since he's been here, he played in a grand final, and off the field has had a significant impact on everyone at the club.
"It's always sad when someone of his age has to retire, but there's also positives in that he's made significant improvements in his health. We've been given every indication he'll be able to live a normal life and that is far more important than him playing football.
"We're sad to see Te Maire go given he's such a great bloke, but he'll always be welcome at our club and we'll never forget what he's done for us in his time here."