The Bornean orangutan, Pongo pygmaeus, is a species of orangutan native to the island of Borneo. Together with the Sumatran orangutan, it belongs to the only genus of great apes native to Asia. Like the other great apes, orangutans are highly intelligent, displaying advanced tool use and distinct cultural patterns in the wild. Orangutans share approximately 97% of their DNA with humans.

The Bornean orangutan has a life span of 35-45 years in the wild; in captivity it can live to be about 60. A survey of wild orangutans found that males weigh on average 75 kilograms (170 lb), ranging from 50–100 kilograms (110–220 lb), and 1.4–1.8 metres (4.6–5.9 ft) long; females average 38.5 kilograms (85 lb), ranging from 30–50 kilograms (66–110 lb), and 1–1.2 metres (3.3–3.9 ft) long.

The Bornean orangutan is an endangered species, with deforestation, oil-palm plantations and killing posing a serious threat to its continued existence.

The Bornean orangutan and the Sumatran orangutan diverged about 400,000 years ago. There has been a continued low level of gene flow between them since then. The two orangutan species were considered merely subspecies until 1996, following sequencing of their mitochondrial DNA.