Paul Langmack captained Canterbury 13 times and played a club-record 84 consecutive first-grade games for the Bulldogs.
The three-time premiership winner died suddenly on Thursday morning, aged 61; he reportedly suffered a massive heart attack.
Bulldogs general manager Phil Gould led tributes, while the club announced his death on its website.
"It is with deep sadness that the Canterbury-Bankstown Bulldogs advise of the sudden passing of club legend Paul Langmack," the club posted.
Langmack joined Canterbury in 1983, making 174 first-grade appearances across eight seasons and winning titles in 1984, 1985 and 1988.
He also played 10 tour matches for Australia, four State of Origin games for NSW and represented NSW City.
His honours included Rugby League Week Player of the Year in 1992 and Dally M captain of the year in 1995.
Gould, who coached Langmack for his final Canterbury premiership, said: "I am devastated to learn of Paul's sudden passing this morning."
"Paul would contact me every day of the week about something to do with rugby league. I'm going to miss those calls and messages."
After leaving Canterbury at the end of 1990, Langmack played for Western Suburbs and the Sydney City Roosters before retiring in 1999.
He later worked as an assistant coach at the Wests Tigers and coached South Sydney in 2003 and 2004.
Langmack was nominated for the Berries to Bulldogs 70 Year Team of Champions in 2004 and received club life membership in 2011.
Gould said Langmack supported Bulldogs community initiatives and created mental health programs for young people and current and former players.
"He was always thinking of other people. This is a significant loss to so many."
"A true Bulldog."