NEW YORK (Reuters) - George Steinbrenner, one of the most colorful and controversial figures in U.S. sports who helped the New York Yankees reclaim their place as the most successful franchise in baseball, died Tuesday at age 80.

New York Yankees owner George Steinbrenner watches his team play the Philadelphia Phillies during the first inning of a spring training baseball game at George M. Steinbrenner Field in Tampa, Florida, March 8, 2010. REUTERS/Steve Nesius

Known as “The Boss” for his tempestuous style, Steinbrenner was loved by Yankees fans, feared by his players and managers and hated by his rivals.

The long-time Yankees owner resurrected the team from a period of decline, returning it to glory in the 1970s.

His family and baseball club announced his death but did not give a cause. Media reports said he had a massive heart attack at his home in Tampa, Florida.

“Winning is the most important thing in my life, after breathing,” Steinbrenner once said.

Willing to spend heavily to sign star players, he demanded results and got them as the Yankees won seven World Series titles and 11 American League pennants since he bought the fabled club in 1973. The Yankees won their record 27th World Series title in 2009.

“He took, literally, a dying franchise and turned it into arguably the greatest franchise in American sports and along the way probably saved baseball,” said Sal Galatioto, president of Galatioto Sports Partners, a sports banking firm that has done business with the Yankees.

“It’s a great loss to the Yankee players and fans,” said Easwall Semper, 65, a lifelong fan wearing a Yankees cap in midtown Manhattan. “He was a fair man. He had his own ways.”

Steinbrenner was twice suspended from baseball -- once for making illegal contributions to President Richard Nixon’s 1972 re-election campaign and then for hiring a private investigator to dig up information on one of his players.

To broader audiences, he was a running joke on the “Seinfeld” sitcom in which the George Costanza character went to work for the Yankees. The Steinbrenner character -- voiced by Larry David and played by Lee Bear -- was always shown from behind, often rambling on while Costanza walked away.

A $10 MILLION BARGAIN

But Steinbrenner had mellowed in recent years, particularly after his club went on a streak of winning four World Series titles between 1996 and 2000. While he had once fired field managers in fits of anger, he let Joe Torre manage the team for many years without the constant meddling of the past.

With his health failing, Steinbrenner had handed over daily operations of the club to his sons Hal and Hank, who became co-chairmen in May 2008. Hal Steinbrenner assumed control of the Yankees later that year.

The team Steinbrenner bought for $10 million in 1973 is now worth $1.6 billion, nearly twice as much as any other in baseball, Forbes magazine estimated.

The Yankees also own around 40 percent of YES Network, a regional cable operation that broadcasts the team’s games. It was valued at around $3 billion in 2007, when the Yankees and other stakeholders looked at selling it.

“George was The Boss, make no mistake. He built the Yankees into champions and that’s something nobody can ever deny,” former Yankees great Yogi Berra, who was fired by Steinbrenner less than a month into the 1985 season, said in a statement.

“George and I had our differences, but who didn’t? We became great friends over the last decade and I will miss him very much.”

‘I AM TOUGH’

Steinbrenner died on the same day as one of baseball’s signature events -- the annual all-star game to be played on Tuesday night in Anaheim, California. His death came two days after that of another Yankees legend, announcer Bob Sheppard.

The family said the funeral would be private but there would be an additional public service.

“It’s a difficult time, on a great day for baseball, the All-Star Game, something everyone looks to; a great man in baseball passed,” Yankees manager Joe Girardi told a news conference in Anaheim.

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“He’s meant so much to not only this organization, but to the game of baseball, and to all of us personally.”

Steinbrenner, who turned 80 on the U.S. Independence Day holiday on July 4, was a well-known figure in popular culture, routinely pictured on the back pages of New York’s tabloids wearing his familiar white turtleneck under a blue blazer.

His early days with the Yankees were chronicled in several books, including “The Bronx Zoo” by player Sparky Lyle and “Ladies and Gentlemen, The Bronx is Burning” by Jonathan Mahler, which was dramatized in a 2007 TV miniseries with Steinbrenner’s character played by Oliver Platt.

“I am tough. Sometimes I’m unreasonable,” Steinbrenner said. “I have to catch myself every once in a while.”

He would publicly chastise underperformers and was famous for his confrontations with manager Billy Martin, who he hired and fired five times, and star Reggie Jackson, who Steinbrenner signed to a big free-agent contract in 1977, the year the Yankees won their first World Series since 1962.

“He had a real loyalty to people, even those people that he fired. Bill Martin is the perfect example,” Yankees executive Rick Cerrone told Fox News.

The son of a wealthy Ohio shipping magnate, Steinbrenner followed in his father’s footsteps as a hurdler at school then earned a masters’ degree in physical education and worked as an assistant college football coach.

He helped revitalize his father’s shipbuilding firm and fed his love of sports by buying a pro basketball team, the Cleveland Pipers, before his defining opportunity came.

The Yankees, baseball’s most glamorous franchise with a history of beloved players such as Babe Ruth, Lou Gehrig, Joe DiMaggio and Mickey Mantle, ran into hard times at the end of Mantle’s career in the late 1960s.

In 1973, Steinbrenner led a group of private investors in buying the Yankees from the Columbia Broadcasting System and threw himself into the day-to-day operations. He would become as prominent as any of the highly paid stars on his team.

“He’s more than just an owner to me. He’s a friend of mine. He will be deeply missed,” Yankees captain Derek Jeter said.

“I think he’s a father figure to everyone that was in our organization in the past or present, because he really took care of his players.”

Steinbrenner is survived by his wife Joan, his sisters Susan Norpell and Judy Kamm, his children Hank, Hal, Jennifer and Jessica, and his grandchildren.