South African Archbishop Desmond Tutu is retiring from public life.
The Nobel Peace Prize laureate announced earlier this year that he would retire on his 79th birthday, which falls on Thursday, to spend more time with his family.
U.S. President Barack Obama called Tutu a "moral titan" who will be missed.
Obama said Tutu has been a voice of principle, an unrelenting champion of justice and a dedicated peacemaker.
Tutu played a pivotal role in South Africa's struggle against apartheid, the now-abolished system of white-minority rule.
He also has advocated freedom and justice worldwide, supported gay rights and pushed for treatment programs to stop the spread of HIV/AIDS.