There are fewer than 100 Sumatran rhinos left in the world following the death of Malaysia's last male.
Tam, who had lived on a wildlife reserve in Borneo after being found wandering in a palm oil plantation in 2008, was announced dead on Monday. The sole Sumatran rhino in Malaysia is now a female named Iman.
It is currently believed that Tam, who was 30, died of old age. A post-mortem will provide more information.
The Sumatran rhino, which used to be prevalent across much of Asia, has now almost disappeared from the wild. Current estimates put its entire population at between 30 and 100. The species has been affected by habitat loss and fragmentation, as well as poaching.
While some fear the threat of extinction - it is listed as critically endangered by the International Union for Conservation of Nature - others believe the species can be saved, including Cathy Dean, CEO of the London-based charity, Save the Rhino International.
"Sumatran rhinos have really suffered from the fragmentation of their habitat," she said. "With logging, with roads for development, the patches of forest available are shrinking. Frankly, it's hard for them to find each other to mate and breed successfully.
"There are a few animals in captivity in the Sumatran rhino sanctuary, and we're trying to get those to breed as fast as we can."
Efforts to breed Tam were unsuccessful.