The former Labor MP, who passed away on Sunday night, spent 15 years in politics, first in the seat of Keira before moving to Wollongong.

He was instrumental in everything from Aboriginal Affairs and Bob Carr's apology to the Stolen Generations, through to the Wollongong Entertainment Centre, the University of Wollongong, the environment, the Illawarra Steelers and lobbying for funds to improve the Science Centre.

"There's no doubt at all that he was an advocate on a whole range of issues," said David Campbell, who succeeded Mr Markham in the seat of Keira.

"Probably too many to even start to list. There was just an absolute confidence in the future of the place that he had."

Mr Campbell said it wasn't just the major issues that would get Mr Markham's attention, he would help anyone who walked through his door.

"There would literally be thousands of individuals who would put their hand up and say 'yeah, I went and saw Col and he gave me a hand on something that was personal'," Mr Campbell said.

The Illawarra's state and federal Labor MPs labelled Mr Markham as someone who served the region with distinction.

"He was celebrated in the Indigenous community of the Illawarra, South Coast and NSW, and was appointed Parliamentary Secretary for Aboriginal Affairs from 1999 to 2003," the statement read.

"His strong and enduring commitment to Indigenous Australians continued throughout the remainder of his life.

"We extend our deepest condolences to Colin's wife Melissa, without whose dedicated love and support his service and achievements would not have been possible, and to his three sons and grandchildren."

The popular MP also served on the board of the Illawarra Steelers, and former Steelers chairman and club life member Peter Newell said Mr Markham was a "Steeler down to his bootlaces".

"He loved rugby league and in the Steelers' earliest days he and beloved wife Melissa opened their home and family to accommodate young players coming from the bush to the club, starting relationships that have blossomed to this day," Mr Newell said.

"He served as a Steelers director for many years, playing an active role in the construction and opening of the Burelli St licensed club and in football operations generally, resulting in his being awarded club life membership."

Working as a mine electrician for 26 years, Mr Markham was inspired to join the Labor Party after the 1975 constitutional crisis.

Mr Markham entered state politics in 1988 when he won the newly established seat of Keira by just a few hundred votes.

He would retain the seat in 1991 and 1995, before Labor infighting saw him change seats and win Wollongong in 1999.

His run ended in 2003 when he lost preselection to Noreen Hay.

During his time as an MP, Mr Markham was appointed as Shadow Minister for Aboriginal Affairs. Early in that role, he and wife Melissa took a two-week trip through Aboriginal communities in NSW.

"That fortnight shocked us both into a realisation that what was happening in this state was absolutely appalling," he said to the Mercury in 2004.

He became the Parliamentary Secretary for Aboriginal Affairs in NSW Premier Bob Carr's 1999 government.

During his years in the position, he played a key role in keeping reconciliation high on the agenda, culminating in an official apology by Mr Carr to the Stolen Generations.

He was a pioneer in other ways too - almost two decades ago he stood up in Parliament and called for an end to plastic bags.

"[My wife and I] are still using the same bags that we purchased eight years ago," he told Parliament.

"This is a good opportunity for all of us to make a real commitment to waste minimisation.

"All honourable members should use calico bags for their grocery shopping."

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