Al Gore, joint winner of the 2007 Nobel Peace Prize, is a former US vice-president now most famous as a campaigner for action to combat climate change.
A member of the US's political aristocracy, most of his early life was spent preparing for high office.
For eight years, he was Bill Clinton's vice-president.
He then ran for the White House himself, losing narrowly to George Bush in 2000 after a court battle over the disputed result in Florida.
"I am Al Gore, and I used to be the next president of the United States," is his standard self-deprecating line of introduction.
After the election, George Bush withdrew US support for the Kyoto climate change pact.
But Al Gore dedicated himself to the cause, producing the campaigning film An Inconvenient Truth, which won an Academy Award for best documentary this year.
He describes climate change as "the most serious crisis our civilisation has ever faced".
Mr Gore was born in Washington on 31 March, 1948. His father was a member of the House of Representatives for the Democratic Party, and later a Senator.
His mother stopped his childhood violin lessons saying: "Future world leaders do not play the violin."
He enlisted to fight in Vietnam, despite his opposition to the war, in order to spare his father any political embarrassment.
In 1977, aged only 28, he won his father's old seat in the House, and moved to the senate eight years later.
In 1988 he launched an audacious bid for the Democratic Party's White House ticket.
The campaign flopped, but he picked himself up and, setting a pattern that he would repeat 12 years later, earned respect with a best-selling book on the need for new policies to avert environmental disaster.
Mr Gore's eloquence on the subject of global warming in the years since his 2000 defeat has won him a new generation of admirers, and fuelled speculation that he could still run for the presidency in 2008.
He has tried to dampen down those rumours.
"I don't have any plans or intentions to be a candidate again and really the main reason is I'm involved in a different kind of campaign," he said in July.
Married in 1970, he and his wife Tipper have four children.
Mrs Gore is well known for her campaigns against what she believes is the corrupting influence of rock music lyrics.