Author and social commentator Celia Lashlie has died after a battle with pancreatic cancer.
A statement on her website said her sudden departure was unexpected but her passing was peaceful.
It said her family was grateful for the love and support expressed by thousands of New Zealanders.
Ms Lashlie's illness had been made public in a statement released only yesterday, which said her condition had deteriorated significantly in the last six weeks.
A statement published on Ms Lashlie's website, quoting her, said: "Late last year I slowly became unwell. The stress of the lifestyle I was living, the demands I made of myself, the demands other people made of me and expected to meet became too great and as 2014 closed I was diagnosed with pancreatic cancer that had spread to my liver. No treatment, no cure, only palliative care. I'd waited too long to look after myself and my body broke."
Ms Lashlie wrote and gave talks on how to raise boys and social justice issues.
She worked for 15 years in the prison service, starting in December 1985 as the first woman to work as a prison officer in a male prison in New Zealand.
Her final role in the prison service was as manager of Christchurch Women's Prison, a position she left in September 1999.
She has written three books: The Journey to Prison: Who goes and why, He'll Be Ok, Growing Gorgeous Boys into Good Men and The Power of Mothers: Releasing Our Children.
Celia Lashlie spoke to Radio New Zealand about parenting and social justice issues numerous times over recent years. Listen to more interviews here.