His son, Dominic O'Sullivan, announced the death on his Facebook page.
"Hei aitua hoki, kua hinga toku matua," he wrote.
"I am profoundly sad to share that my father, Emeritus Professor Sir Vincent O'Sullivan, died in Dunedin late yesterday. I was present with his wife Helen.
"In the next day or two, Vince will travel to the Home of Compassion in Island Bay, where he will repose ahead of his Requiem Mass later in the week at St Mary of the Angels, Wellington.
"Requiescat in Pace."
Born in Auckland on September 28 in 1937, Sir Vincent combined an academic career with that of a prolific writer and editor.
He graduated from Auckland and Oxford universities, and lectured in English at Victoria and Waikato universities before becoming literary editor of the New Zealand Listener.
Six years of fellowships at New Zealand and Australian universities followed, interrupted by a year as resident playwright of Wellington's Downstage Theatre where the first of his several stage plays was performed in 1983.
Called Shuriken, it deals with the fateful misunderstandings which led to the death of 50 Japanese prisoners of war and a New Zealand guard at Featherston in 1943.
O'Sullivan concentrated mainly on poetry in his earlier years, with 11 volumes published beginning with Our Burning Time in 1965.
But in the 1970s, he turned increasingly to short stories which have been published in five collections, starting with The Boy, The Bridge, The River.
Death and other forms of loss, deprivation and betrayal are central themes.
In 1988, O'Sullivan resumed his academic career as professor of English literature at Victoria University.
His novel Let the River Stand won the Montana Book Award in 1994 and was followed by others including Believers to the Bright Coast.
He edited eight volumes of writing by Katherine Mansfield, and several anthologies of New Zealand poetry, and wrote studies of James K Baxter and John Mulgan.
Sir Vincent was Knighted in December 2021.
'One of our greatest writers'
Fergus Barrowman, publisher at Te Herenga Waka University Press, posted on social media that he was "not ready" for Sir Vincent's death.
"He'll be one of our greatest writers, and I think that the popular regard and the critical regard is only going to grow as people read and read more deeply and start connecting the dots between the disparate parts of his ire," Barrowman told RNZ's Morning Report programme on Monday.
"The first time I met Vincent was 40 years ago when I was a young assistant editor here at the University Press, and we were working on the publication of his play Shuriken, which was about the massacre of Japanese prisoners of war at the camp in Featherstone - a wonderful play, and one that's sort of deeply moral and quite critical of aspects of New Zealand society.
"And I think I really got Vincent as a character and as a writer through that work across a number of genres within the literary world."
Barrowman said the "breadth of his talent was quite extraordinary".
"He was a prolific poet in his 20s, and those early collections of poems - which he sometimes didn't sample in his latest selected poems - are really worth tracking down because, you know, you can see a young writer sort of discovering an enormous talent.
"And he's gone on. He's always been a very adaptable writer and he's always been a restless writer who's tried out new things."
Barrowman had been working on a new collection of poetry by Sir Vincent before his passing, which he said contained "new and distinctive flavours" of writing.
'Right up there at the top'
Dame Fiona Kidman said Sir Vincent played a big part in shaping literature in New Zealand.
"He was an anthologist. He produced some very important anthologies in which he included both well-known people and people who were not well-known. And he supported younger writers and writers who were not so well-known, to make a platform for their work."
In an interview with RNZ's Midday Report, Dame Fiona said all his work was done with excellence and he had a mind that would never stop.
"It was difficult to think of somebody in Wellington in those early years when I first knew him, in the '70s, who didn't have a Vincent story, some bit of quick wit that they could repeat and pass on. He was just such an amazing rapporteur.
"But he was also, I have to say, one of the most generous of men. I was in awe of him in those early years.
"He was somebody who I think helped to shape New Zealand literature in those early years. And so, there were many levels to the person that I knew."
Dame Fiona said in the pantheon of great New Zealand writers, Sir Vincent "must be right up there at the top".
"He was whatever he turned his hand to, and it was enormous. The breadth of his work is absolutely huge.
"Remember, too, that he edited Katherine Mansfield's letters that he produced, vast quantities of research into her life, and anything that he did was done with excellence - he had a passion for excellence.
"He was a very politically aware person very observant of what was going on in the world, but his mind never seemed to stop."
