Agathis australis, commonly known by its Māori name kauri (pronounced ['kɑːʉɾi]), is a coniferous tree in the family Araucariaceae, found north of 38°S in the northern regions of New Zealand's North Island.

It is the largest (by volume) but not tallest species of tree in New Zealand, standing up to 50 m tall in the emergent layer above the forest's main canopy. The tree has smooth bark and small narrow leaves. Other common names to distinguish A. australis from other members of Agathis are southern kauri and New Zealand kauri.

With its novel soil interaction and regeneration pattern it can compete with faster growing angiosperms. Because it is such a conspicuous species, forest containing kauri is generally known as kauri forest, although kauri need not be the most abundant tree. In the warmer northern climate, kauri forests have a higher species richness than those found further south. Kauri even act as a foundation species that modify the soil under their canopy to create unique plant communities.