Giant koala
Temporal range: Pleistocene
Phascolarctos stirtoni
An artist's illustration of Phascolarctos stirtoni along side the modern Phascolarctos cinereus (koala)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Infraclass: Marsupialia
Order: Diprotodontia
Family: Phascolarctidae
Genus: Phascolarctos
Species: P. stirtoni
Binomial name
Phascolarctos stirtoni
Bartholomai, 1968

The Giant Koala (Phascolarctos Stirtoni) is an extinct genus of arboreal marsupial from Pleistocene Australia. It was a close relative to the smaller extant Koala, only bigger. It was about a third larger than a koala and weighed more compared to the koala today. Just like its modern day descendent, it is believed that it solely ate eucalyptus leaves, making it a folivore (an animal who only eats leaves). It even coexisted with the modern koala for a short time before becoming extinct 50,000 years ago. It is the largest tree-dwelling marsupial that ever lived. It is estimated to have weighed 15 kg, and to some extent, probably 20 kg.