Mr. Knievel's death was confirmed by his granddaughter, Krysten Knievel. He had been in failing health for years, suffering from diabetes and pulmonary fibrosis, an incurable condition that scarred his lungs.
He had undergone a liver transplant in 1999 after nearly dying of hepatitis C, likely contracted through a blood transfusion after one of his bone-shattering spills.
Immortalized in Washington's Smithsonian Institution as "America's Legendary Daredevil," he was best known for a failed 1974 attempt to jump Snake River Canyon on a rocket-powered cycle. With a TV audience watching, the chute on his Skycycle X-2 deployed early, sending the cycle into the canyon wall. It landed partly in the river, but Mr. Knievel walked away with minor injuries.
He spent almost a month in a coma in 1968 after he crashed while jumping the fountains at the Caesars Palace casino-hotel in Las Vegas. There were more serious injuries when he tried to clear a tank full of sharks in Chicago in 1976.
"Anybody can jump a motorcycle," he once told Esquire magazine. "The trouble begins when you try to land it."
He suffered nearly 40 broken bones - including his back seven times - before he retired in 1980.
"If you don't know about pain and trouble, you're in sad shape," he told Esquire. "They make you appreciate life."
Though Mr. Knievel dropped off the pop culture radar in the '80s, the image of the high-flying motorcyclist clad in patriotic, star-studded colors was never erased from public consciousness. He always had fans and enjoyed a resurgence in popularity in recent years.
He died just days after it was announced that he and rapper Kanye West had settled a federal lawsuit over the use of Mr. Knievel's trademarked image in a popular West music video.
Mr. Knievel made a good living selling his autograph and endorsing products.
He had a knack for outrageous yarns: "Made $60 million, spent 61. ...Lost $250,000 at blackjack once. ... Had $3 million in the bank though."
He began his daredevil career in 1965 when he formed a troupe called Evel Knievel's Motorcycle Daredevils, a touring show in which he performed stunts such as riding through fire walls, jumping over live rattlesnakes and mountain lions, and being towed at 200 mph behind dragster race cars. In 1966 he began touring alone, barnstorming the West and doing everything from driving the trucks, erecting the ramps, and promoting the shows.
In the years after the Caesars crash, the fee for Mr. Knievel's performances increased to $1 million for his jump over 13 buses at Wembley Stadium in London - the crash landing broke his pelvis - to more than $6 million for the attempt to clear the Snake River Canyon in Idaho. On Oct. 25, 1975, he jumped 14 Greyhound buses at Kings Island in Ohio.
Mr. Knievel also dabbled in movies and TV, starring as himself in Viva Knievel and with Lindsay Wagner in an episode of the 1970s TV series Bionic Woman. George Hamilton and Sam Elliott each played Mr. Knievel in movies about his life.
Evel Knievel toys accounted for more than $300 million in sales for Ideal and other companies in the 1970s and '80s.
Born Robert Craig Knievel in the copper mining town of Butte, Mont., on Oct. 17, 1938, Mr. Knievel was raised by his grandparents. He traced his career choice back to the time he saw Joey Chitwood's Auto Daredevil Show at age 8.
He starred in track and field, ski jumping, and ice hockey at Butte High School.
He was dubbed "Evil Knievel" by a jailer in Montana after crashing his motorcycle while fleeing police. He later changed the spelling to "Evel" as his daredevil career took off to avoid being perceived as a bad guy.