EVEL Knievel, the hard-living, death-defying adventurer who went from stealing motorcycles to riding them in a series of spectacular airborne stunts in the 1960s and '70s, has died. He was 69.

Knievel had been in failing health for years with diabetes and idiopathic pulmonary fibrosis, an incurable lung condition. In 1999 he underwent a liver transplant after nearly dying of hepatitis C, which he believed he had contracted through a blood transfusion after one of many violent spills.

Only days before his death, he and rap artist Kanye West settled a lawsuit over West's use of Knievel's trademarked image in a music video.

Knievel amazed and horrified onlookers in 1968 by vaulting his motorcycle 45 metres over the fountains of Caesars Palace in Las Vegas, only to land in a bone-breaking crash.

He continued to win fame and fortune by getting huge audiences to watch him roar his motorcycle up a ramp, fly over 10, 15 or 20 cars parked side by side and come down on another ramp. Perhaps his most spectacular stunt, another disaster, was an attempt to jump an Idaho canyon on a rocket-powered motorcycle in 1974.

Knievel's showmanship, skill and disdain for death were so admired that he became a folk hero.

Performing stunts hundreds of times, Knievel repeatedly shattered bones as well as his bikes. When he was forced to retire in 1980, he told reporters that he was "nothing but scar tissue and surgical steel".

He underwent as many as 15 major operations to relieve severe trauma and repair broken bones — skull, pelvis, ribs, collarbone, shoulders and hips. "I created the character called Evel Knievel, and he sort of got away from me," he said.

His health was also compromised by years of heavy drinking; he said at one point he was consuming half a bottle of whiskey a day, washed down with beer chasers.

Robert Craig Knievel was born in the copper-mining town of Butte, Montana, and raised by grandparents.

As he told the story, he acquired the name Evel as a boy. Arrested for stealing hubcaps, he was taken to jail, where the police were holding a man named Knofel, whom they called "Awful Knofel".

They decided to call Robert "Evil Knievel". The name stuck, and some years later, Knievel legally took the name Evel, changing the "i" to "e" because he thought it looked better.