Oz was an independently published, alternative/underground magazine associated with the international counterculture of the 1960s. Editor Richard Neville first published the magazine in Sydney in 1963, launching a parallel version of Oz in London from 1967.

In both Australia and the UK, the creators of Oz were prosecuted on charges of obscenity. A 1963 charge was dealt with expeditiously when, upon the advice of a solicitor, Neville and Sydney co-editors Richard Walsh and Martin Sharp pleaded guilty. In two later trials, 1964 Australia and 1971 UK, the magazine's editors were acquitted on appeal, after initially being found guilty and sentenced to harsh jail terms. The Australian publication folded in 1969, while Neville's London co-editors Jim Anderson and, later, Felix Dennis, then Roger Hutchinson published the British Oz until 1973.

The original Australian editorial team included university students Neville, Walsh and Sharp, and Peter Grose, a cadet journalist from Sydney's Daily Mirror. Other early contributors included art critic Robert Hughes and future author Bob Ellis. Neville, Walsh and Sharp had each been involved in student magazines at their respective Sydney tertiary campuses: Neville had edited the University of New South Wales student magazine Tharunka, Walsh edited its University of Sydney counterpart Honi Soit and Sharp had contributed to the short-lived student magazine The Arty Wild Oat while studying at the National Art School in East Sydney. Influenced by the radical comedy of Lenny Bruce, Neville and friends decided to found a "magazine of dissent".

The 16-page first issue, published on April Fools' Day 1963, caused a sensation, selling 6,000 copies by lunchtime of publication day. It parodied the Sydney Morning Herald (and was even printed on The Herald's own presses, adding to its credibility) and led with a front-page hoax about the collapse of the Sydney Harbour Bridge. It also featured a centre spread on the history of the chastity belt and a story on abortion – based on Neville's own experience of arranging a termination of pregnancy for a girlfriend; abortion was then still illegal in New South Wales. These stories though, would soon lead to the magazine's first round of obscenity charges, but there were also more immediate consequences. As a result of the controversy generated by the abortion story, the Sydney Daily Mirror cancelled its advertising contract, it also threatened to sack Peter Grose from his cadetship unless he resigned from Oz and the Maritime Services Board evicted Oz from its office in The Rocks.

In succeeding issues (and in its later London version) Oz gave pioneering coverage to contentious issues such as censorship, homosexuality, police brutality, the Australian government's White Australia policy and Australia's involvement in the Vietnam War, as well as regularly satirising public figures, up to and including Australian Prime Minister Robert Menzies.

In mid-1963, shortly after the publication of issue No.3, Neville, Walsh and Grose were summoned on charges of distributing an obscene publication; the shock of the charges caused Walsh's deeply religious father to suffer a serious heart attack, so their family solicitor arranged for the case to be adjourned until September 1963 but he advised the trio that, as first offenders, they could avoid having their conviction recorded if they pleaded guilty.

Word soon went around the publishing trade; after their current printers pulled Issue 4 from the presses Neville shopped around for a new printer but he was turned down by a dozen other companies until, on Sharp's advice, he approached maverick writer-publisher Francis James, editor of the Anglican Press, who agreed to take it on. When Neville, Walsh and Grose appeared in court on 3 September 1963 the Walshes' solicitor pleaded guilty on their behalf; each was fined £20 and their convictions were recorded, an outcome that was to have serious repercussions in their second trial.

With end-of-year exams looming, Oz issue No.5 was postponed until the Christmas break. When eventually issued, it included a scathing satire on the ongoing police harassment of gay people. "The Stiff Arm of the Law" (which became a regular feature on police misconduct) featured a parody of a police report in which incriminating sections of a supposed account of an officer's real actions in a gay-bashing incident were crossed out and replaced with far more anodyne language, e.g. in the line "I was at Phillip Street Station in my homo hunting togs", the words "homo hunting togs" were crossed out and replaced with the handwritten words "plain clothes", "this little bastard" with "a youth", and "I myself punched him several times" was amended to read "I was punched several times", and so on. As a result of this perceived slight to their integrity, police seized 140 copies of Oz from a Kings Cross, NSW newsagent and took them to a magistrate, who ordered them to be burned.