The Wondiwoi tree-kangaroo (Dendrolagus mayri) is a critically endangered, bear-like mammal native to tropical mountain forests on the island of New Guinea in Western Papua.

It is a species of tree-kangaroo (genus Dendrolagus), a group of long-tailed, bear-like animals native to Australia and New Guinea that mostly live in trees and feed on plant matter.

[3] D. mayri was located in the Wondiwoi Peninsula of West Papua at an elevation of 1,600 metres (5,200 ft) within montane rain forest.

[8][9] Smith was investigating Vireya rhododendrons in an unexplored area of the Wondiwoi ranges and photographed a "dorianus type" tree kangaroo at an altitude of approximately 1,600 metres.

[12] More recent DNA analysis indicates, however, that the members of the dorianus group deserve species status, although Dendrolagus mayri itself was not included in the study.

The Tree Kangaroo Conservation Program (TKCP) involves local communities and researchers communicating to effectively preserve tree-kangaroos while understanding the culture and traditions of the indigenous people.

Although the mountain forests in this peninsula are remote, hunting can still be a big concern, due to the rarity of this species, which requires these areas to be safeguarded.