OK, OK, not an Australian, a New Zealander but hey, we adopt all the good Kiwis.
This guy is a tuatara, one of the most archaic of all living reptiles. Part of the order Sphenodontia, his name is derived from the maori language and means "peaks on the back". Go look him up on google, he's an amazing little guy.
And listed as vulnerable to extinction just like a lot of NZ's magnificent wildlife as they're getting caned by imported predators against which they have no defence.