William "Wild Bill" Hagy started out as just another Orioles fan from Dundalk who loved his Budweiser in Section 34 of the upper deck at Memorial Stadium.

But with his sloping gut, fluffy beard and straw hat, he cut a striking visual. And eventually his O-R-I-O-L-E-S cheers, replete with dramatic contortions of his out-of-shape body, became the emotional fulcrum as crowds at Memorial urged the baseball team to improbable comebacks in the late 1970s and early 1980s.

Mr. Hagy, a cabdriver in everyday life, died yesterday at his Arbutus home. He was 68. The cause of death had yet to be determined.

Many trace the birth of "Orioles Magic" to June 22, 1979, the day a Doug DeCinces home run gave the eventual pennant winners a come-from-behind victory over the Detroit Tigers. Mr. Hagy cheered that moment and many more.

"For a team that didn't draw very well, it was very refreshing to see someone who actually came out to the ballpark and generated interest," said Orioles Hall of Fame pitcher Jim Palmer. "He loved the Orioles. And I'm all for people who are in that category."

"Of course, it was unbelievable," said longtime friend George "Skip" Dorer, who met him while working on a book about the 1979 Orioles. "That place rocked, and he was at the center of it."

Mr. Hagy became such a fixture that he was allowed to climb atop the Orioles' dugout to rally the crowd with his act. He was so popular that all he had to do was stand in his section to get the crowd roaring. For a generation of Orioles lovers, he was the quintessential fan.

"He'd say he was just going to get a beer or go to the bathroom," said Wayne Kaiser, his friend of almost 30 years and roommate, "but then, all of a sudden, you'd see him up on the dugout leading cheers."

He met Presidents Jimmy Carter and Ronald Reagan, was written up in the New Yorker and signed more than his share of autographs.

"To those of us who were close to him, we were sort of enthralled to be around this famous guy," Mr. Kaiser said. "He never got a big head about it. But he enjoyed how the fans responded to him. He was a die-hard hometown guy, and he liked that he could get people excited about the team he loved."

The Orioles had planned to observe a moment of silence in his memory last night, but the game at Camden Yards was rained out.

"The Orioles organization is deeply saddened to learn of the passing of 'Wild Bill' Hagy," the club said in a statement. "While leading cheers from 'The Roar from 34' at Memorial Stadium, Wild Bill became a Baltimore institution. ... He will be missed by everyone who knew him and by everyone for whom he led the 'O-R-I-O-L-E-S' cheer. All of us in the Orioles organization extend our sincere condolences to his family and friends."

Former Orioles catcher Rick Dempsey would sometimes join Mr. Hagy on the dugout to lead cheers. If Mr. Dempsey thought the team needed a lift, he'd signal Mr. Hagy by waving a white towel from the bullpen. Wackiness usually ensued.

"I just remember how much control he had over the crowd," Mr. Dempsey said. "In an era when the Orioles were on fire, he turned the crowd on fire. He was a huge part of the Orioles Magic era."

Mr. Hagy was born on Sparrows Point and attended Sparrows Point High School.

He began attending Orioles games with his father during the team's first season in 1954.

"Brooks and Frank Robinson, Jim Palmer, Rick Dempsey, he loved them all as long as they were loyal to the Orioles," Mr. Kaiser said.

As a young man, Mr. Hagy drove an ambulance and then a Good Humor ice cream truck. But for most of his professional life, he drove a taxi for Jimmy's, County and North Point cab companies. He retired in January 2004.

"He enjoyed being his own boss," Mr. Kaiser said. "He could work as little or as much as he wanted."