The Bornean orangutan is a species of orangutan endemic to the island of Borneo. Together with the Sumatran orangutan and Tapanuli orangutan, it belongs to the only genus of great apes native to Asia. It is the largest of the three species of orangutans. Like the other great apes, orangutans are highly intelligent, displaying tool use and distinct cultural patterns in the wild. Orangutans share approximately 97% of their DNA with humans. Also called mias by the local population, the Bornean orangutan is a critically endangered species, with deforestation, palm oil plantations, and hunting posing a serious threat to its continued existence.

Orangutans are great apes native to the rainforests of Indonesia and Malaysia. They are now found only in parts of Borneo and Sumatra, but during the Pleistocene they ranged throughout Southeast Asia and South China. Classified in the genus Pongo, orangutans were originally considered to be one species. From 1996, they were divided into two species: the Bornean orangutan and the Sumatran orangutan. A third species, the Tapanuli orangutan, was identified definitively in 2017. The orangutans are the only surviving species of the subfamily Ponginae, which diverged genetically from the other hominids between 19.3 and 15.7 million years ago.