Lonesome George, a giant tortoise believed to be the last remaining of its subspecies, died on Sunday of unknown causes, the Galapagos National Park said.
With no offspring and no known individuals from his subspecies left, Lonesome George became known as the rarest creature on Earth.
He was estimated to be about 100 years old, which made him a young adult as the subspecies can live up to an age of 200.
Lonesome George was first seen in 1972 by a Hungarian scientist on the Pinta island, one of the smallest islands in the Galapagos.
Environmentalists had believed that his subspecies had become extinct.
Scientists had been trying to get George to mate since 1993, when they introduced two female tortoises of a different subspecies into his pen.
They laid eggs twice, but they were infertile.
With his death, the Pinta giant tortoises are expected to be extinct.
The Galapagos' giant tortoise population was declimated after the arrival of humans.
Tortoises were hunted for their meat by sailors and fishermen to the point of extinction.
Their habitat has been eaten away by goats introduced from the mainland.
We never forget; the speed of tortoises' walk can be much faster than that of their extinction.