The first man to set foot on the moon, renowned US astronaut Neil Armstrong, has died, his family announced Saturday, prompting glowing tributes to his achievements and notably humble character.

Armstrong, who inspired a generation to reach for the stars, underwent cardiac bypass surgery earlier this month after doctors found blockages in his coronary arteries, but he died following subsequent complications. He was 82.

Praising Armstrong as a "reluctant American hero," his heartbroken relatives expressed hope his legacy would encourage young people to "work hard to make their dreams come true, to be willing to explore and push the limits and to selflessly serve a cause greater than themselves."

Armstrong and fellow Apollo 11 astronaut Edwin "Buzz" Aldrin landed on the moon's desolate surface on July 20, 1969.

His first words upon stepping on the lunar surface have since been etched in history: "That's one small step for (a) man, one giant leap for mankind."

The estimated 500 million people who watched the grainy black and white broadcast breathed a sigh of relief when Armstrong told mission control the module had landed safely, saying: "Houston, Tranquility base here. The Eagle has landed."

But the lunar pioneer, who was decorated by 17 countries and received a slew of US honors, was never comfortable with his worldwide fame, shying away from the limelight.

Armstrong even stopped signing memorabilia after learning his autographs were being sold at exorbitant prices.

John Glenn, the first American to orbit Earth, recalled Armstrong's legendary humility.

"He didn't feel that he should be out huckstering himself," the former Ohio senator told CNN. "He was a humble person, and that's the way he remained after his lunar flight, as well as before."

A "deeply saddened" President Barack Obama on Saturday hailed Armstrong as "the greatest of American heroes -- not just of his time, but of all time."

His "legacy will endure -- sparked by a man who taught us the enormous power of one small step," said Obama, who was just under eight years old at the time of the historic Apollo 11 mission.

Republican House Speaker John Boehner remembered Armstrong as a "true hero."

"Ohio has lost one of her proudest sons. Humanity has gained a legend," Boehner said.

Aldrin said he had hoped that he, Armstrong and Michael Collins, the third astronaut on the mission, would have met up in 2019 for celebrations marking the 50th anniversary of Apollo 11. But the occasion will not come to pass.

"Whenever I look at the moon, it reminds me of the moment over four decades ago when I realized that even though we were farther away from Earth than two humans had ever been, we were not alone," Aldrin said.

Collins, in a statement released by a NASA spokesman, said of Armstrong: "He was the best, and I will miss him terribly."

Australian Prime Minister Julia Gillard said the astronaut's death "marks the end of an amazing era in human progress."

"His example of service, accomplishment and modesty... will never die."

Born in Wapakoneta, Ohio on August 5, 1930, Armstrong had an early fascination with aircraft and worked at a nearby airport when he was a teenager.

He took flying lessons at the age of 15 and received his pilot's license on his 16th birthday.

A US Navy aviator, he flew 78 missions in the Korean War.

Armstrong joined NASA's predecessor agency, the National Advisory Committee for Aeronautics, in 1955.

As a research pilot at NASA's Flight Research Center in Edwards, California, he flew on many pioneering high-speed aircraft, eventually flying over 200 different models, including helicopters, gliders, jets and rockets.

He reached astronaut status in 1962, and was assigned as command pilot for the Gemini 8 mission, during which he performed the first successful docking of two vehicles in space.

After retiring from NASA in 1971, Armstrong taught aerospace engineering at the University of Cincinnati for nearly a decade and served on the boards of several companies, including Lear Jet, United Airlines and Marathon Oil.

He also worked as deputy associate administrator for aeronautics at NASA headquarters, coordinating and managing the space agency's aeronautics research and technology tasks.

His family said they had a simple request to people in memory of Armstrong's life.

"Honor his example of service, accomplishment and modesty, and the next time you walk outside on a clear night and see the moon smiling down at you, think of Neil Armstrong and give him a wink," it said.