Tasmanian oak  refers to the hardwood produced by three trees: Eucalyptus regnans, Eucalyptus obliqua or Eucalyptus delegatensis, when it is sourced from the Australian state of Tasmania. Despite the common name 'oak', none of the species are in the genus Quercus.
The hardwood timber is light-coloured, ranging from straw to light reddish brown. It is used in construction, including panelling and flooring, for furniture, and also for reconstituted board and high quality paper. 
The species are also widely known by their common names. Eucalyptus obliqua is known as stringybark or messmate, Eucalyptus regnans is known as mountain ash, and the closely related Eucalyptus delegatensis is known as alpine ash or woollybutt.