OZ was an underground alternative magazine. First published in Sydney, Australia, in 1963, a second version appeared in London, England from 1967 and is better known.

The original Australian OZ took the form of a satirical magazine published between 1963 and 1969, while the British incarnation was a "psychedelic hippy" magazine which appeared from 1967 to 1973. Strongly identified as part of the underground press, it was the subject of two celebrated obscenity trials, one in Australia in 1964 and the other in the United Kingdom in 1971. On both occasions the magazine's editors were acquitted on appeal after initially being found guilty and sentenced to harsh jail terms. An earlier, 1963 obscenity charge was dealt with expeditiously when, upon the advice of a solicitor, the three editors pleaded guilty.

The central editor throughout the magazine's life in both Australia and Britain was Richard Neville. Co-editors of the Sydney version were Richard Walsh and Martin Sharp. Co-editors of the London version were Jim Anderson and, later, Felix Dennis.