Australian National Anthem is "Advance Australia Fair".
It was written by Peter Dodds McCormick - a Scottish born composer in Australia.
The song was first performed in 1878 in Sydney, but used to be just a partiotic song, snd didn't become the national anthem until 1977.
McCormick wrote the song pretty much on a bus home from a concert of the world's national anthems where Australia was not represented.
The song was often used but not chosen as the official national anthem until in the 1970s there was a competition, with other suggestions being Waltzing Matilda (the inofficial national anthem to this day), and Song of Australia.