The rhetorical pugilist whose popularity ratings are the envy of other leaders across Canada said he's stepping down next Friday to pursue undisclosed business interests.
Williams fought tears as he stood before a packed news conference Thursday. He said his health is good and it's time to get off what he called a sometimes bruising 10-year ride on the roller-coaster of public life.
"I have indeed been so, so lucky and it is very, very hard to say goodbye," he said as his family, cabinet members and staff looked on. Many of his closest supporters cried openly as he spoke.
Williams said the $6.2-billion deal unveiled just last week to develop the proposed Lower Churchill hydroelectric project in Labrador convinced him to go.
"Orson Welles once said that if you want a happy ending, you need to know when to end your story. So I've called you here today to announce the end of my story as the ninth premier of Newfoundland and Labrador."
Williams, 61, later told reporters that he's not getting any younger. He said he wanted to leave enough time for his Progressive Conservative party to elect another leader, likely this spring, before a fixed-date election slated for next October.
Williams was unapologetic earlier this year as his decision to have heart-valve surgery in Florida set off an international debate about public-versus-private health care.
"My heart, my choice," he said at the time.
As he prepares to step out of the political limelight, Williams highlighted his province's bolstered sense of self-worth.
"I am most proud of our renewed pride as a people," he said to thunderous applause and occasional shouts of "Danny!"
"I'm proud when I travel the country and meet expatriates who tell me what a difference it is now to be a Newfoundlander and Labradorian living on the mainland because those people who once thought we were the poor cousins of Confederation now see us as a province on the move.
"It has indeed been a great honour to serve as premier of Canada's youngest and coolest province."
Williams has locked horns with everyone from Prime Minister Stephen Harper to provincial doctors in his sometimes zealous defence of political stances.
Harper's Conservatives were shut out of all seven federal seats in the province in 2008 when Williams led a bitter "Anything But Conservative" campaign over offshore royalties and equalization payments.
Relations have since thawed, and Harper had only good things to say Thursday about his former nemesis.
"His enormous popularity in the province is a tribute to his hard work and commitment, and his very personal connection to the people," the prime minister said in a statement. "A tireless champion for the people of Newfoundland and Labrador, Mr. Williams accomplished a great deal in his seven years as premier."
Williams was acclaimed leader of the Progressive Conservative party in 2001 and was elected premier in 2003, leading the party to a landslide victory.
He was re-elected with an even larger majority in October 2007, buoyed by high-profile clashes with the offshore oil industry, Harper and Quebec.
Williams lashed out again Thursday at those "who deemed us unworthy of great success and chose to restrict us." It was a thinly veiled shot at the refusal of Quebec to renegotiate grossly lopsided terms of the Upper Churchill hydroelectric deal.
The 1969 agreement to ship power from Labrador to Quebec for sale has reaped $19 billion in profits for Quebec, versus $1 billion for Newfoundland and Labrador, says the province. The deal did not reflect rising energy values and does not expire until 2041.
Quebec Premier Jean Charest refused to bite Thursday when asked by reporters about the squabble.
"Believe me, I've heard what he has had to say with regard to his relationship with Hydro-Quebec," he said. "But I've known Danny Williams for a number of years. ...We got elected around 2003 and we've done a lot of good things together. So I can only wish Danny all the best."
Williams leaves amid a nasty dispute with 1,100 doctors in the province who've been without a contract for more than a year. Fourteen medical specialists have threatened to quit en masse on Feb. 4, saying they're unfairly paid and overworked in a politically toxic environment.
The premier also made headlines in recent months for accusing a Quebec judge of bias in a legal fight over his government's botched seizure of a polluted AbitibiBowater mill.
And he recently upset people on the Burin Peninsula by saying that Marystown Mayor Sam Synard is a grandstander who "doesn't count" because Synard questioned whether the province is doing enough to land a major shipbuilding contract.
Williams didn't deny his combative ways as he spoke Thursday.
"I laugh when critics and some reporters say that I'm nothing more than a fighter ... never happy unless I'm taking someone on.
"Well folks, I am here to tell you today that those people are right," he said to laughter from the standing-room-only crowd at the legislature.
And if you think Williams is tough, you should meet his mom.
"I could have choked them," 85-year-old Teresita Williams said with a boisterous laugh when asked about her son's critics. The white-haired lady who Williams called his ultimate political adviser sat beaming in the front row as he announced his departure.
"You've got to take the good with the bad, I'd say, when you get involved in politics," she said. "I think he did a great job."
The premier's tenure came as revenues from the province's offshore oil industry soared. In 2008, his government announced that Newfoundland and Labrador would stop collecting equalization payments and shed its so-called 'have-not' status for the first time in its history.
Before he entered public life, Williams was a criminal lawyer and a cable TV mogul. A Rhodes scholar, he earned the nickname ''Danny Millions'' after selling Cable Atlantic for $232 million in 2000.
But he also took great care in fashioning his image as an every man, rubbing shoulders with outport fishermen with just as much ease as he worked the backrooms of oil executives. He also donates his annual legislative salary to his family's charitable foundation.
Deputy premier Kathy Dunderdale will take over his duties, making her the first female premier in the province's history. Both the provincial Liberal and NDP parties are also led by women.
"For a province that has a history of old boys' clubs and networks, it's a very symbolic moment," said Alex Marland, a political scientist at Memorial University in St. John's.
The premier's departure changes everything for a Tory party that would likely have sailed through the next election with a majority victory, he said.
"He can't be replaced. Period," Marland said.