Sudan, the world’s last male northern white rhino, died after “age-related complications,” researchers announced Tuesday.

The 45-year-old rhino was euthanized Monday after his conditions “worsened significantly” and he was unable to stand any longer, the Ol Pejeta Conservancy in Kenya said in a statement.

There are now only two northern white rhinos left in the world – both are female.

"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 Richard Vigne, the group’s CEO.

The last male northern white rhino had been born in Sudan, taken to a Czech zoo and then transferred in 2009 to Kenya, where had become a bit of a celebrity.

Last year, Sudan was listed as “The Most Eligible Bachelor in the World” on the dating app Tinder.

Sudan "significantly contributed to the survival of his species as he sired two females," the conservancy said. "Additionally, his genetic material was collected yesterday and provides a hope for future attempts at reproduction of northern white rhinos through advanced cellular technologies."

"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." — Richard Vigne

Hopes of saving the species now lie with Najin, 27, and her daughter, Fatu 18 – which are both at Ol Pejeta. A fourth female northern white rhino died in the San Diego Zoo in 2015.

Najin and Fatu are both capable of reproducing – but the surrogacy process is complicated and pricey. The rhinos also get 24-hour anti-poaching security in Kenya, a country where poaching is a big problem.

The animals are poached for its horns, which can cost hundreds of thousands of dollars because some believe it has medicinal value. The illegal rhino horn trade has even helped finance the terrorist group al-Shabab, which has made millions slaughtering rhinos and elephants for ivory.

“Giving birth to just one rhino won’t save the species,” Elodie Sampere, communications manager for the conservancy, told Fox News earlier this month. “We need at least 10 babies.”

Fox News’ Paul Tilsley and the Associated Press contributed to this report.