In four years as a royal commissioner he managed to enrage waterside thugs to the point where two police bunked at his flat.
And he infuriated Kerry Packer so greatly the billionaire's memorial service became the vehicle for a beyond-the-grave swipe.
But friends had the final say last night on a gentle lawyer of unshakeable principle.
Premier John Brumby hailed Mr Costigan, 78, as an eminent lawyer and an active campaigner for social justice.
"He will be remembered for intellect, integrity and for his fearless commitment to exposing corruption and crime," Mr Brumby said.
Former premier John Cain declared Mr Costigan a life-long and trusted friend.
"He was a great bloke . . . quiet and strong," he said.
Law Institute chief executive Michael Brett Young said Mr Costigan was "thorough and fearless".
And Victorian Bar Council chairman John Digby, QC, said he was "very self-effacing but very charming, good-natured, warm and humble".
Family spokesman Gerry Costigan said his Uncle Frank was a funny, private man who had managed to work until about six months ago.
Mr Costigan died peacefully yesterday morning surrounded by his children.
Born in Depression-era Preston of Irish Catholic parents, Mr Costigan was one of eight children.
First schooled by Jesuits, and then at Melbourne University, he became a solicitor in 1953, a barrister in 1957 and a Queen's Counsel in 1973.
As a young lawyer, Mr Costigan became active in the ALP, standing for the unwinnable seat of Chisholm.
Mr Cain said he was a political ally in Labor's dark time following the DLP split, and remained a good friend for life.
Ironically, it was a Liberal Party appointment that put Mr Costigan in the spotlight.
In 1980 prime minister Malcolm Fraser asked him to head the Royal Commission on the Activities of the Federated Ship Painters and Dockers Union.
It became known as the Costigan Royal Commission and after four years had uncovered a tangle of dodgy tax evasion schemes.
When the pin was pulled on the commission in 1984 by prime minister Bob Hawke, files were passed to the fledgling National Crime Authority.
One case study linked Mr Packer to organised crime including tax evasion, drugs, murder, fraud and pornography. Mr Costigan's team called Mr Packer "The Squirrel". Media chose the moniker Goanna. It stuck.
Mr Packer outed himself as the Goanna, but denied the allegations. Labor Attorney-General Lionel Bowen spoke in Parliament, effectively clearing the mogul.
Mr Costigan's star dimmed, though the royal commission is still seen as a landmark blow against organised crime.
"Some might think that to go in hard as he did was a bad career move, but that was the measure of the man," Mr Cain said last night.
Mr Costigan continued legal and community work, and was a familiar figure in Melbourne's legal precinct.
He chaired the Bar Council and worked with Jesuit Social Services for 21 years until last October.
Its chief executive, Julie Edwards, said Mr Costigan had great insight, great intellect and great compassion".
"And he had a wicked sense of humour, just a bit of a glint in the eye, an Irish leprechaun kind of thing. It was a pretty wonderful mix."
Frank Costigan QC dies | Herald Sun
Any man who goes after even Packer has my vote.
