Māori historian, educator and writer Dr Ranginui Walker has passed away at the age of 83.
His body is expected to be taken to Ōrākei Marae.
Dr Walker worked as a primary school teacher before later becoming Head of Māori studies at Auckland University.
Prime Minister John Key says he was saddened to hear of Dr Walker's death.
"He was not only an insightful commentator on important historical and contemporary issues, but was a tireless and passionate advocate for Māori," he said.
"I always enjoyed seeing Dr Walker, and felt privileged when he sent me copies of his work.
"Dr Walker was a leader by example, who will be missed by many. My thoughts are with his whānau and friends at this time."
AUT University history professor Dr Paul Moon said Dr Walker's death signifies a huge loss.
"I think you find in academia there are a lot of people who become quite aloof and that’s unfortunate," he said.
"He was very much aware of who his audience was and what his message and beliefs were.
"He was, I thought, extraordinarily effective at communicating those [his message and beliefs], and he continued that all the way through his career."
Green Party co-leader Metiria Turei says she has learnt a lot from Dr Walker and will miss him.
"Dr Walker was held in huge esteem throughout New Zealand and by many of us in the Green Party," Ms Turei said.
"I have been on many panels with Ranginui and he has always been open to a fiery debate. He was incredibly well-informed, highly opinionated, and always willing to have an open conversation.
"As a Māori activist lawyer, then politician, I have always had a lot to learn from listening and watching kaumātua like Ranginui Walker. The Green Party and I will miss him.
"Dr Walker wrote that the quest for a fair partnership under the Treaty was ‘struggle without end’. Despite his passing, his work in helping to bring new generations together in a better understanding of that partnership endures," she said.
In the 1970s he was a member of Ngā Tama Toa, an activist group that championed the rights of Māori and fought racial prejudices.
Dr Walker authored many Māori historical books and was a nominated for 2016 New Zealander of the Year.