A longtime resident of Venice who also was known as a photographer, artist and collector of modern art, Hopper died at his home of complications from prostate cancer, said Alex Hitz, a friend of the family.
A frail-looking Hopper, whose battle with prostate cancer was revealed in October, was able to attend a ceremony for the unveiling of his star on the Hollywood Walk of Fame in late March.
In a more than five-decade acting career that was influenced early on by working with James Dean and studying at the Actors Studio, he made his film debut as one of the high school gang members who menace Dean in the 1955 classic "Rebel Without a Cause."
Hopper went on to appear in more than 115 films, including "Apocalypse Now," "Cool Hand Luke," "Giant," "Hang 'Em High," "Rivers Edge," "Rumble Fish," "Speed," "The American Friend," "True Grit" and "True Romance."
But it's his role as the long-haired, pot-smoking biker Billy opposite Peter Fonda's Wyatt (Captain America) in the hit movie "Easy Rider" that gave Hopper his most enduring claim to fame.
The low-budget tale of two bikers on an ultimately tragic cross-country odyssey after scoring a big cocaine sale, "Easy Rider" became a generational touchstone.
"We rode the highways of America and changed the way movies were made in Hollywood," Fonda said in a statement Saturday. "I was blessed by his passion and friendship."
The movie, which boasted a star-making performance from a little-known Jack Nicholson as a boozy small-town lawyer who goes along for the ride and gets his first taste of marijuana, set old-guard Hollywood back on its heels.
"The impact of 'Easy Rider,' both on the filmmakers and the industry as a whole, was no less than seismic," Peter Biskind wrote in his 1998 book "Easy Riders, Raging Bulls: How the Sex-Drugs-And-Rock 'n' Roll Generation Saved Hollywood."
"Hopper was catapulted into the pantheon of countercultural celebrities that included John Lennon, Abbie Hoffman and Timothy Leary," Biskind wrote. "He was surrounded by groupies and acolytes. He may have started down the slippery slope to megalomania and grandiloquence on his own, but he had plenty of help."
"Easy Rider" won an award at the Cannes Film Festival for the best movie by a new director, and it earned co-writers Hopper, Fonda and Terry Southern an Oscar nomination.
"Hopper and Fonda were renegades, Hollywood-bashers, the Vietcong of Beverly Hills," Biskind wrote. "To them, it was vindication, beating Hollywood at its own game, proof that you could get high, express yourself and make money all at the same time."
Commenting on the success of "Easy Rider," Hopper said: "Nobody had ever seen themselves portrayed in a movie. At every love-in across the country people were smoking grass and dropping LSD, while audiences were still watching Doris Day and Rock Hudson."
Another signature role was in "Apocalypse Now," director Francis Ford Coppola's 1979 nightmare vision of the Vietnam War. Hopper played a counterculture photojournalist, who is encountered in the compound of Marlon Brando's insane, renegade Col. Kurtz and is prone to his own crazed rantings.
"Dennis Hopper was part of that sort of misfit, rebel-persona generation where you just didn't hit your mark and say your lines and try to create a movie icon type of presence," said Peter Rainer, film critic for the Christian Science Monitor. "He was much more rough-hewn, rough-edged and intuitive as an actor, and this created a lot of problems early on."
Indeed, Hopper survived being shut out of major studio films for a number of years after a legendary run-in in the late '50s with old-guard director Henry Hathaway on the set of "From Hell to Texas."
The highly volatile actor also survived his own well-documented descent into drugs and alcohol that reached a low point in the early '80s while making a film in Mexico.
"I ended up walking off into the jungle, naked, in the middle of the night, somewhere down near Cuernavaca," he told Entertainment Weekly in 2005. "I was convinced they were listening to my mind and my friends were being gassed."