Oz, officially the Sydney-Melbourne Conurbation, is a fictional mega-city in the Judge Dredd

Judge Dredd

Judge Joseph Dredd is a comics character whose strip in the British science fiction anthology 2000 AD is the magazine's longest running . Dredd is an American law enforcement officer in a violent city of the future where uniformed Judges combine the powers of police, judge, jury and executioner...

 comic, located in the south east of Australia. It was the main setting for the Judge Dredd strip Oz

Oz (Judge Dredd story)

Oz is a mini-series featured in the comic 2000 AD, running for 26 episodes from 24 October, 1987 to 16 April, 1988....

. Like most of the mega-cities of the time Oz is ruled by a Judge

Judge (2000 AD)

Judge is a title held by several significant characters in the Judge Dredd series, which appears in the British comics 2000 AD and Judge Dredd Megazine...

 system. According to the Judge Dredd D20 RPG Oz was where the sport of sky surfing

Sky-surfer

Sky-surfing is a fictional sport practiced in the world of the British Judge Dredd comic books, often featuring the champion sky-surfer Chopper. It is like ordinary surfing, but is done on a surfboard rigged with anti-gravity that floats in the air. The surfer stands on the board and controls its...

began.