The world's last male northern white rhino has died after "age-related complications", researchers have announced.
Sudan, aged 45, was put to sleep after his condition "worsened significantly" and he was no longer able to stand, the Ol Pejeta Conservancy in Kenya said. His muscles and bones had degenerated and his skin had extensive wounds, with a deep infection on his back right leg.
Sudan was part of an ambitious effort to save the subspecies from extinction after decades of decimation by poachers, with the help of the two surviving females. One is his daughter, Najin, and the other is her daughter, Fatu.
The conservancy said Sudan "stole the heart of many with his dignity and strength".
"He was a great ambassador for his species and will be remembered for the work he did to raise awareness globally of the plight facing not only rhinos, but also the many thousands of other species facing extinction as a result of unsustainable human activity," said the conservancy's CEO, Richard Vigne.
- Archive: ITV News Africa Correspondent John Ray meets Sudan in 2015
Sudan became something of a celebrity, attracting thousands of visitors and was listed as "the most eligible bachelor in the world" on the Tinder dating app last year as part of a fundraising effort.
Born in Sudan, he was the last of his kind to be born in the wild. He was taken to a Czech zoo and then transferred to Kenya in 2009 with the three other remaining fertile northern white rhinos at the time.
The rhino "significantly contributed to the survival of his species as he sired two females", the conservancy said.
Researchers hope that genetic material collected from Sudan could be used in the future for the reproduction of northern white rhinos "through advanced cellular technologies".
Sudan's death "is a cruel symbol of human disregard for nature and it saddened everyone who knew him, but we should not give up", said Jan Stejskal, director of international projects at Dvur Kralove Zoo in the Czech Republic.
"It may sound unbelievable, but thanks to the newly developed techniques even Sudan could still have an offspring," he said.
Northern white rhinos once roamed parts of Chad, Sudan, Uganda and the Central African Republic, and were particularly vulnerable because of the armed conflicts that have swept the region over decades.
Other rhinos, the southern white rhino and another species, the black rhino, are under heavy pressure from poachers who kill them for their horns to supply illegal markets in parts of Asia.
Roughly 20,000 southern white rhinos remain in Africa. Their numbers dipped below 100 around a century ago, but an intense effort initiated by South African conservationist Ian Player in the mid-20th century turned things around.