Pan Pan, the world's oldest male panda has died in China aged 31, six months after being diagnosed with cancer.
His more than 130 descendants account for a quarter of the world's captive-bred panda population.
Born in the wild in Sichuan in China, he was taken into captivity when he was just a few months old.
The world's oldest female panda is currently 36-year-old Basi, who also lives in China, after Jia Jia died aged 38 in Hong Kong in October.
Wild pandas usually live to about 20.'Hero father'
Pan Pan, whose name means "hope" or "expectation", died early on Wednesday morning at the Dujiangyan base of the China Conservation and Research Center for Giant Panda, also in Sichuan.
The centre described the news of the death of the "hero-father" panda as "heart-wrenching".
Keepers said he had stopped moving and eating, and lost consciousness, as his health had deteriorated rapidly over the preceding three days.
In September, the International Union for Conservation of Nature announced that the status pandas had been changed from "endangered" to "vulnerable", as numbers had begun to increase.
The latest Chinese estimates show a population of 1,864 adults, as well as - according to China's State Forestry Administration - 422 in captivity.
But the IUCN warns that climate change is predicted to wipe out more than one third of the panda's bamboo habitat in the next 80 years.