The main page of Knievel's Web site displayed his picture in his trademark red, white and blue outfit, and the legend "Robert Craig 'Evel' Knievel -- Oct. 17, 1938 -- Nov. 30, 2007."
The cause of death was not immediately known. Knievel had suffered from diabetes and pulmonary fibrosis, a disease of the lungs, and he had a liver transplant eight years ago.
Knievel billed himself as "the greatest motorcycle stunt rider of all time," and had the scars and stories to prove it.
A highlight film of his hundreds of motorcycle jumps shows him soaring to record lengths over buses, landmarks and other obstacles, but also skidding, slamming and falling in a series of crashes.
During his career, he jumped farther, higher and over more objects than anyone else.
In 1974, Knievel wanted to jump the Grand Canyon, but was rebuffed by the National Park Service. He settled for an attempt to soar a "jet" powered cycle over the Snake River Gorge in Idaho.
The heavily promoted fiasco ended when thousands of fans saw Knievel climb into his "Sky-Cycle" and proceed to plummet into the river below, barely escaping with his life.