mX is an Australian free afternoon daily newspaper in the cities of Melbourne, Sydney and Brisbane, owned and produced by News Limited. Targeted at commuters, its main channels of distribution are inner-city railway stations, tram and bus stops, and major CBD intersections.

The first mX was published in Melbourne on Tuesday 6 February 2001, hoping to capitalise on the Metro format, popular in Europe. The paper contains lighter news and sports articles, often containing strange stories and facts from around the world (under the headings "Nice One" and, "What The?"). The newspaper's approach is a much greater focus on entertainment than news than broadsheet newspapers, or even other tabloids.

Melbourne Express, published by rival Fairfax Media, was this paper's competitor. Initially it used the same format, although it was released in the mornings rather than the afternoon. It began publication the day before mX, but was soon overtaken due to mX's much broader use of colour, its greater availability, and its lighter tone. In addition, mX had no explanation at its launch, allowing readers to assume that it stood for "Melbourne Express" and that it was the paper known by that name. Melbourne Express ceased publication on 7 September 2001.