SYDNEY, AUSTRALIA - JULY 28: Boyd Cordner of the Roosters runs the ball during the round 19 NRL match between the Bulldogs and Roosters at ANZ Stadium on July 28, 2019 in Sydney, Australia. (Photo by Mark Evans/Getty Images)

21 players have officially retired from the NRL since the start of the 2021 calendar year, while another is unlikely to return to the sport.

The list kicked off before the season had even begun, with Malakai Watene-Zelezniak and Cameron Smith confirming their decisions to retire from the sport, the former over kidney failure and the latter after a long off-season of deliberation.

Injuries have led to plenty of players pulling the pin mid-season, with the Sydney Roosters being the most impacted club.

All of Jake Friend, Boyd Cordner and Brett Morris retired before the season was half done.

Elsewhere, Blake Green, Justin O'Neill, Michael Morgan, Justin O'Neill and Russell Packer have all been bitten by injury, bringing an end to their careers.

The Roosters continued to be bitten by retirement in the off-season, with Josh Morris and mid-season recruit Dale Copley hanging up the boots.

Josh Dugan decided to retire after off-field dramas this year, while other stalwarts of the game in Alex Glenn, Issac Luke, Trent Merrin, Iosia Soliola and Anthony Don also called time on their careers.

Former NRL player Sonny Bill Williams also called time on his sporting career, while Blake Ferguson has declared he has played his last NRL game, with the 31-year-old set to give rugby union a shot.

Roger Tuivasa-Sheck is also on the list. He may well return to the competition in the future, however, rugby union has called his name for the time being, with the 28-year-old former New Zealand Warrior unlikely to return until at least after the next World Cup in 2023.

Full list of retiring players

Leeson Ah Mau (New Zealand Warriors)
Sonny Bill Williams (Former NRL player)
Boyd Cordner (Sydney Roosters)
Dale Copley (Sydney Roosters)
Anthony Don (Gold Coast Titans)
Josh Dugan (Cronulla Sharks)
Blake Ferguson (Parramatta Eels)
Jake Friend (Sydney Roosters)
Alex Glenn (Brisbane Broncos)
Blake Green (Newcastle Knights)
Issac Luke (Brisbane Broncos)
Trent Merrin (St George Illawarra Dragons)
Michael Morgan (North Queensland Cowboys)
Brett Morris (Sydney Roosters)
Josh Morris (Sydney Roosters)
Justin O'Neill (North Queensland Cowboys)
Russell Packer (Wests Tigers)
Cameron Smith (Melbourne Storm)
Iosia Soliola (Canberra Raiders)
Roger Tuivasa-Sheck (New Zealand Warriors)
Malakai Watene-Zelezniak (Wests Tigers)