Image copyright AP

Famed American anti-war activist Tom Hayden has died aged 76.

Hayden died in his home in Santa Monica "after a lengthy illness", the Los Angeles Times reports.

He was a member of the "Chicago seven" charged with conspiracy over anti-Vietnam war protests in 1968 and eventually acquitted.

Hayden later served in the California state assembly and Senate for nearly two decades. He was married to actress Jane Fonda between 1973 and 1990.

Born in Michigan in 1939, he became an activist during his time at the University of Michigan, where he helped to found Students for a Democratic Society (SDS).

While there, he wrote a policy document called the Port Huron Statement, which he styled the "agenda for a generation".

Mr Hayden and the SDS went on to become a major influence on the 1960s protest movement, particularly against the Vietnam war.

"Rarely, if ever, in American history has a generation begun with higher ideals and experienced greater trauma than those who lived fully the short time from 1960 to 1968,'' he wrote in the essay Streets of Chicago.

Image copyright AP Image caption Hayden married famous actress and fellow anti-war activist Jane Fonda in 1973

In 1968, Mr Hayden was part of a controversial anti-war demonstration in Chicago, timed to coincide with the Democratic National Convention.

The protest turned violent, with eight people - including Mr Hayden - charged with conspiracy and crossing state lines to incite a riot.

The so-called Chicago seven trial - originally the Chicago eight, before one defendant was tried separately - ran for years, with appeals and retrials. Mr Hayden was eventually cleared of all charges.

In 1973, he married actress Jane Fonda, who was herself an outspoken critic of the Vietnam War. She was internationally famous and wealthy, while he was still seen in some quarters as an anti-establishment troublemaker.

Image copyright AP Image caption By 1988, Mr Hayden was an elected official at the California assembly, and writing his memoir, "Reunion"

He would go on to reinvent himself in the coming decades, moving away from the image of a long-haired student protester.

He turned his attention to mainstream politics in the late 1970s, earning himself a place in the California State Assembly in 1982. A decade later, shortly after his divorce from Fonda, he moved on to the California Senate.

He also became a prolific writer of books and essays, and served as a columnist for several outlets.

Fifty years after he wrote the Port Huron statement, about a generation "looking uncomfortably to the world we inherit", he wrote that the concentration of wealth in the hands of the elite was a "mountain untouched" .

Writing in The Guardian in 2012, he called the Occupy Wall Street protests a "new force in the world".

"The Occupy movement, and kindred spirits from the Middle East to China, is driven by young people who feel unrepresented by the institutions, disenfranchised economically, and threatened by an environmental catastrophe," he said.

"The direct action movement of the early 1960s was similar in nature."

Hayden married actress Barbara Williams in 1993, and had a son, Liam.

Image copyright Twitter Image caption Actress Martha Plimpton was among those who paid tribute

Tributes to the iconic protester-turned-politician emerged on social media following his death.

Clara Jeffery, editor of left-leaning investigative magazine Mother Jones, said: "Tom Hayden lived a cinematically full life; any one of these chapters worth a biopic."

Mayor of Los Angeles, Eric Garcetti, said "a political giant and dear friend has passed."

"Tom Hayden fought harder for what he believed than just about anyone I have known," he tweeted.