But some of those who only saw him on the television or in the newspaper, sticking up for the worst criminals, may have wondered why he was held in such high esteem.
He was a criminal defence lawyer, a profession that normally languishes near the bottom of "most trusted" polls. Even lower than journalists.
"I'm sorry but if he was such a gifted lawyer why didn't he work for the prosecution?" was one on-line comment to a Herald editorial on King's death.
"How can I admire someone who works to allow criminals go free?"
Such comments are typical of the widespread public misunderstanding of the role of defence lawyers, says Auckland barrister Ron Mansfield, who has been in the middle of a number of high-profile cases.
Defence lawyers are there to bring balance to the justice system, to ensure that the court hears all the relevant submissions or evidence to make the right decision, he explains.
"If there was not balance, then there would be injustice frequently. When we think about it, that is what we want for ourselves and family."
Though the majority of cases are resolved with pleas of guilty before a trial, Mansfield says the original charges laid against a defendant are often too many or too high or the asserted "facts" are incorrect.
"Making sure someone pleads guilty to a charge that reflects what they have done and that they are sentenced fairly is essential.
"Everyone wants to get it right. We work hard, long hours, lose sleep and worry a lot that we do just that. The scariest thing for anyone involved in justice is getting it wrong."
The role can be isolating. Most of the time, it is only the defence lawyer standing up for the rights of their client against the power and resources of the State.
"Most people consider that people accused of crime, especially serious crime, do not have any (rights)," says Mansfield.
"As a result they do not look favourably on anyone who does that. There can be a lot of anger and frustration."
Their clients have often been "seriously let down" by the community: poorly housed and educated, with severe physical and mental health problems.
"They are scared, stressed and not trusting of anyone. Their lives are often ruined and they are desperate."
Building trust and forging a genuine relationship is difficult, but essential to the lawyer-client bond.
"Once you have that trust the weight of that is often enormous and hard to bear," Mansfield says.
But the work is rewarding - and strangely addictive.
"Helping or making a positive change feels good and is good. That is probably why we do it. That is probably why we continue to do it."
As well as those charged with murder, rape, fraud and drugs, Mansfield also has a strong social justice streak. He stood up for the Greenpeace activists including Lucy Lawless, the Occupy Auckland protesters and went in to bat for cameraman Bradley Ambrose in the "Tea Tapes" saga.
This year he represented Evans Mott, the Auckland boatbuilder charged with assisting the suicide of his wife Rosie. Mott quickly admitted the offence, which has a maximum penalty of 14 years in prison.
The case reignited the euthanasia debate and, after lengthy submissions from Mansfield, 56-year-old Mott was discharged without conviction by Justice Patricia Courtney.
It's the sort of result Greg King would have cheered for; a hard-fought win for the underdog who had suffered enough.
His death follows the loss of another legal giant, John Haigh, QC who, at 65, suffered a fatal brain haemorrhage in April.
Haigh was one of the most highly respected lawyers in the country, a formidable legal mind with a deep sense of social justice, a family man with integrity who loved a good prank.
Yet, despite the universal praise following his death, he was most famous for taking on one of the most unpopular cases in recent memory - the defence of Clint Rickards on sex charges. Rickards was acquitted after Haigh forensically unpicked the Crown case.
Whatever some might think of policemen who engage in group sex with young women, the jury agreed the evidence did not exist to prove guilt beyond reasonable doubt - a key tenet of our justice system.
Yet that doesn't always wash with a sceptical public, according to two members of the bar who until recently were senior Crown prosecutors.
Mina Wharepouri and Rachael Reed are used to being on the "right" side of the law; holding criminals to account for their crimes.
Each has recently moved from Meredith Connell, the private law firm that holds the Crown warrant, to work as barristers in City Chambers - set up by Paul Wicks and his mentor Haigh in 2003.
The move has raised eyebrows among a few of Reed's friends. She believes the role is misunderstood by the wider public.
"Anytime I get a hint of a negative comment, or am asked how I could do it when I know a person is guilty, I say that everyone has the right to a defence," says Reed, whose first brief as defence counsel starts in January.
"It's not for me to judge whether or not they are guilty. That is for a jury."
For all the defence lawyers who act honourably, there have been several recent cases which reinforce the low public opinion of the profession.
There were few tears from colleagues when courtroom veteran Barry Hart was struck off as a lawyer this year.
Hart was found guilty of three charges of professional misconduct in July, including charging a client's family $1000 an hour despite much of the preparation work being done by a junior lawyer who had been practising for only two months.
Judge Dale Clarkson, the head of the Lawyers and Conveyancers Disciplinary Tribunal, was damning in her findings.
Though striking off was a "last resort" for a senior lawyer such as Hart, Judge Clarkson said the "evidence in these proceedings has disclosed a lack of integrity on the part of this practitioner".
An aggravating factor in the tribunal's decision was his "poor disciplinary history", which included seven previous findings against him.
The pattern of behaviour meant the tribunal had "no confidence in either his rehabilitation or protection of the public by ensuring there is no risk of reoffending.
"Having weighed all the evidence and submissions, it is the tribunal's unanimous view that the practitioner is no longer a fit and proper person to practise as a barrister or solicitor."
The consequences are great for the 71-year-old, who has lost a property empire, a fleet of luxury cars and his career in just a few months.
He has lost a "lifetime of earnings" because of the collapse of his rural property portfolio in Waimauku, for which he owes $30 million to the ANZ Bank and is charged $200,000 interest each month.
He has kept a low profile since his fall from grace, but was among the first to pay tribute to his friend King.
"He's helped me and gone beyond the call of duty to assist me both as a friend and as a fellow lawyer in my time of need," Hart was reported as saying.
"Greg was there for me."
Soon after the gruelling trial of Ewen Macdonald ended in his acquittal, King flew to Auckland to represent Hart and try to persuade the disciplinary tribunal to not end his career.
King submitted that Hart was a "victim of his own success", whose popularity as a defence lawyer meant he failed to come to grips with the business side of his law practice.
However, many others in the legal profession struggled to express sympathy for Hart, believing him to be the epitome of why the public distrust lawyers.
A damning report by Dame Margaret Bazley shone the spotlight on taxpayer-funded legal aid, which had ballooned from $111 million in 2006/07 to $172 million three years later.
The term "car boot lawyer" became a common phrase after the publication of the review three years ago, which led to widespread changes in how legal aid was administered.
Bazley, one of New Zealand's most senior civil servants, called for a "sea change" in the system open to abuse by lawyers and defendants.
"While there are very good lawyers in the legal aid system, there is also a small but significant proportion of very bad lawyers who are bringing themselves and their profession into disrepute."
One example of poor practice cited by Bazley was an allegation that up to 80 per cent of lawyers practising in the Manukau District Court could be "gaming" the system by delaying a plea or changing pleas part-way through, to maximise payments.
The claim was widely derided by the criminal bar as "hearsay" evidence, which she acknowledged was an anecdote. But the much wider problems she pinpointed were acted on by former Justice Minister Simon Power.
The Legal Services Agency was shut down and its responsibilities folded into the Justice Ministry, while lawyers had to become accredited to receive legal aid payments.
The Public Defence Service was expanded to more courts around the country, taking up to half the criminal workload, much to the disdain of many private lawyers who did not believe the bulk-funded service was cheaper.
Fixed fees have also been introduced for some criminal, family and civil cases. But the most complex - and therefore expensive - cases like murder and drugs trials are managed on a case-by-case basis.
The most expensive 1 per cent of cases accounted for 26 per cent of spending in 2008/09, according to the Justice Ministry figures.
This creates a new problem - increasing the possibility of a miscarriage of justice.
The Weekend Herald is aware of an upcoming murder trial where a senior lawyer has been funded for just seven hours of preparation time in a case where there is a strong defence for the most serious charge.
"Something needed to be done about legal aid. But the pendulum has swung too far the other way," one experienced Auckland barrister Auckland says.
The reforms mean the legal aid bill is expected to fall to around $102 million by 2013/14. The Government has backed off further reform since Judith Collins took over the portfolio from Power, deferring a decision on whether to change eligibility criteria for certain family and civil cases.
Collins was concerned that the proposed changes did not strike the right balance between fiscal responsibility and protecting the most vulnerable, somewhat at odds with the other hard-line justice reform pushed through by the Government.
And it was the ultimate New Zealand case of injustice that inspired King. Arthur Allan Thomas was locked up in a Turangi prison where King's father was a guard, and his pardon, after nine years in prison, was the catalyst to King's pursuit of a career in law. His dream was to defend innocent people.
He agreed that he had acted for "absolutely horrible bastards", which had given him nightmares, but the right to a fair trial was beyond question.
"Unless we do our job for an individual, the whole society suffers. I really do justify it to myself in those terms," King said in a 2009 interview. "When I stand for someone, I'm standing for the citizen versus the state. I'm not here to be popular, I'm here to do my job."
Defenders of choice
A Weekend Herald straw poll asked more than 20 senior detectives, Crown prosecutors and defence lawyers who they would hire if they faced criminal charges.
These names kept coming up.
If you had money to spend, three Queen's Counsel were at the top of the list. Paul Davison, John Billington and David Jones had reputations for integrity, jury appeal and a sharp forensic mind.
A number of other experienced counsel who were also highly regarded.
Peter Kaye, Paul Wicks, Ron Mansfield, Graeme Newell, Paul Borich, Todd Simmonds and Richard Earwaker were all mentioned numerous times.
