For more on the life and legacy of Sen. Ted Kennedy, watch "World News" at 6:30 p.m. ET and the ABC News Special "Remembering Ted Kennedy" at 10 p.m. ET. Click here for ABC News' full coverage.
The Kennedy boys stormed the national scene in the early 1960s when John F. Kennedy was elected president, Robert Kennedy was named attorney general and Ted Kennedy was elected as a U.S. senator -- a political trifecta.
But outside Washington, they were a close-knit family that had to bear more tragedy than most. President Kennedy's 1963 assassination was followed by Bobby Kennedy's assassination in June 1968, while he was campaigning for his own presidential bid. More than 30 years later, his nephew John F. Kennedy Jr. and his wife died in a 1999 plane crash.
Ted Kennedy himself was injured in a 1969 plane crash and came under fire when he crashed his car on Chappaquiddick, a small island off Martha's Vineyard, killing 28-year-old Mary Jo Kopechne.
But it was his passionate dedication to health care, his constant work on behalf of those who had suffered injustice that is his legacy.
President Obama, awakened with the news of Kennedy's death around 2 a.m. this morning, called Kennedy "the greatest United States Senator of our time."
"Michelle and I were heartbroken to learn this morning of the death of our dear friend, Senator Ted Kennedy," Obama said in a statement released shortly after. "For five decades, virtually every major piece of legislation to advance the civil rights, health and economic well-being of the American people bore his name and resulted from his efforts."
Since Kennedy's brain cancer diagnosis last year, his death was something his family and colleagues knew was unavoidable. But in true Kennedy fashion, he didn't slow down until he had no choice but to do so -- making a memorable stump speech for Obama a year ago at the Democratic National Convention.
Family pictures late this spring show a noticeably weakened Kennedy out on the water in a family boat, but still smiling.
The family reportedly gathered around the senator during his final days, knowing the end was near. There was even talk of his grandchildren not being allowed in the room because he had deteriorated so badly.
"I think it must have been just incredibly difficult for everybody," ABC News contributor Cokie Roberts said this morning on "Good Morning America," " because Ted Kennedy became the father to this whole family."