US TV star Johnny Carson has died at the age of 79, after losing a battle with the respiratory disease emphysema.
Johnny Carson interviewed Groucho Marx as his first Tonight Show guest
The legendary former host of NBC's Tonight Show was surrounded by family and died peacefully, his nephew said.
Carson retired from the top-rated late-night entertainment show in 1992 after 30 years as one of the most popular TV personalities in the US.
President Bush led the public tributes, saying Carson "had a profound influence on American life and entertainment".
In 2002 Carson, who often smoked during his show, was diagnosed with emphysema - a disease associated with smoking.
"Mr Carson passed away peacefully early Sunday morning," said his nephew, Jeff Sotzing.
"He was surrounded by his family, whose loss will be immeasurable. There will be no memorial service."
Carson began his career on television stations in his home state of Nebraska in the late 1940s.
His boyish looks won over both audiences and guests on the Tonight Show, with Carson's appearance on set announced by sidekick Ed McMahon's catchphrase: "Heeeeere's Johnny!"
Carson was America's king of late-night television, dominating it from 1962 to 1992, the BBC's Steve Futterman in Los Angeles says.
In many ways he perfected the late-night chat show, our correspondent says.
It would begin with a fast-paced monologue, usually dealing with events from around the world.
The butt of the jokes was often American presidents, from Kennedy to Nixon to Reagan.
But he was not afraid to laugh at himself - in fact some of the best moments were when a joke failed, our correspondent adds.
He remained popular until his retirement in May 1992, when an estimated 55 million viewers watched him hand over the Tonight Show host duties to comic Jay Leno.
Carson told the audience: "And so it has come to this. I am one of the lucky people in the world. I found something that I always wanted to do and I have enjoyed every single minute of it."
His personal life did not match his career success, however. Carson was married four times and divorced three times.
He choose to let the Tonight Show stand as his finale, withdrawing into a quiet retirement and refusing to become involved in other show business projects.
In 1993, Carson explained his absence from the limelight to the Washington Post newspaper.
"I have an ego like anybody else," he said, "but I don't need to be stoked by going before the public all the time."
He was inducted into the Television Hall of Fame in 1987 and awarded the Presidential Medal of Freedom in 1992.