“Through his fierce dignity and unbending will to sacrifice his own freedom for the freedom of others, Madiba transformed South Africa and moved all of us,” Mr Obama said. “His journey from a prisoner to a president embodied the promise that human beings and countries can change for the better.”
White House aides said Mr Obama was likely to travel to South Africa to attend Mr Mandela’s funeral.
Mr Obama was joined in tribute by all the living American presidents, beginning with George HW Bush, who was president when Mr Mandela walked free from prison in 1991 after 27 years.
“I watched in wonder as Nelson Mandela had the remarkable capacity to forgive his jailers following… wrongful imprisonment – setting a powerful example of redemption and grace for us all,” Mr Bush said.
Bill Clinton, who occupied the White House when Mr Mandela was elected the first black president of South Africa in 1994, had the closest relationship with him of any of the living US presidents.
“Today the world has lost one of its most important leaders and one of its finest human beings, and Hillary, Chelsea and I have lost a true friend,” Mr Clinton said. “We will remember him as a man of uncommon grace and compassion, for whom abandoning bitterness and and embracing adversaries was not just a political strategy but a way of life.”
George W Bush called Mr Mandela “one of the great forces for freedom and equality of our time”.
“He bore his burdens with dignity and grace, and our world is better off because of his example,” Mr Bush said. “This good man will be missed, but his contributions will live on forever.”
Jimmy Carter, the former US president, said: “The people of South Africa and human rights advocates around the world have lost a great leader.
South Africa’s archbishop emeritus Desmond Tutu lauded his compatriot and fellow Nobel peace laureate as the man who taught a deeply divided nation how to come together.
“Over the past 24 years Madiba taught us how to come together and to believe in ourselves and each other. He was a unifier from the moment he walked out of prison,” Tutu said marking Mandela’s passing.
Meanwhile, Nigeria’s president mourned the loss of one of history’s “greatest liberators” in a condolence message to South Africa .
Goodluck Jonathan, the leader of Africa’s most populous country, said “Mandela will always be remembered and honoured by all mankind as one of its greatest liberators, a wise, courageous and compassionate leader, and an icon of true democracy.”
He described the former South African president “as a source of inspiration to the oppressed peoples all over the world.”
Mandela’s “death will create a huge vacuum that will be difficult to fill in our continent,” Jonathan said.
Secretary-General Ban Ki-moon paid his own tribute, saying Mandela was “a giant for justice” whose “selfless struggle for human dignity, equality and freedom” inspired many people around the world.
“No one did more in our time to advance the values and aspirations of the United Nations,” he told reporters soon after Mandela’s death was announced.
Ban said he was deeply touched when he met Mandela in his residence in South Africa in February 2009.
“When I thanked him for his life’s work, he insisted the credit belonged to others,” Ban said. “I will never forget his selflessness and deep sense of shared purpose.”
John Kerry, the US secretary of state, called Mr Mandela “a stranger to hate”.
“He gave everything he had to heal his country and lead it back into the community of nations, including insisting on relinquishing his office and ensuring there would be a peaceful transfer of power,” Mr Kerry said.
Israeli Prime Minister Benjamin Netanyahu, said Nelson Mandela was of “the most honorable figures of our time”.
He went on to say: “He was the father of his people, a man of vision, a freedom fighter who rejected violence. He set a personal example for his people in the long years he spent in prison. He was never arrogant.
“He worked to mend the tears in South African society and with his character managed to prevent outbursts of racial hatred. He will be remembered as the father of new South Africa and as an outstanding moral leader.”
Australian Prime Minister Tony Abbott on Friday hailed Nelson Mandela as “a truly great man” after the anti-apartheid hero died in South Africa aged 95.
“Nelson Mandela was one of the great figures of Africa, arguably one of the great figures of the last century,” Abbott told Fairfax radio, referring to him as the father of modern South Africa.
“A truly great man.”
