Paul Langmack won premierships with Canterbury in 1984, 1985 and 1988, playing 174 games for the club during its 'Dogs of War' era.
He also made 137 appearances for Western Suburbs, played four times for NSW in State of Origin and joined the Kangaroos' 1986 tour of the United Kingdom.
At the Magpies, he formed a close relationship with Tommy Raudonikis.
After his playing career, Langmack coached South Sydney for 35 games across 2003 and 2004.
His appearances on The Footy Show led to the affectionate nickname 'Yesterday's Hero'.
He later worked on NSWRL mental health programs, supporting current and former players, after facing mental health struggles and cancer himself.
Langmack has died aged 61.
Code Sports reported that he suffered a heart attack on Thursday morning and was taken to hospital, where he could not be revived.
He was reportedly in a sauna at the Breakfast Point Country Club gym when the incident occurred.