In science
* Messier 15 (M15), a globular cluster in the constellation PegasusIn firearms and military equipment
* M15 mine, a United States anti-tank mine * M15 rifle, a variant of the M14, a United States military rifle * Grigorovich M-15, a Russian World War I-era biplane flying boat * M15 pistol, a General Officer's variant of the M1911A1 * M15 Half-track * M15/42 tank, an Italian medium tankIn transportation
* M-15 (Michigan highway), a highway in the lower peninsula of Michigan, US * M15 motorway (Hungary), a motorway in Hungary * M15 road (East London), a Metropolitan Route in East London, South Africa * M15 (Cape Town), a Metropolitan Route in Cape Town, South Africa * M15 road (Pretoria), a Metropolitan Route in Pretoria, South Africa * M15 road (Durban), a Metropolitan Route in Durban, South Africa * M15 road (Bloemfontein), a Metropolitan Route in Bloemfontein, South Africa *In sports
* Markku Uusipaavalniemi (nicknamed "M-15"), a Finnish curlerIn computing
* An ergonomic model of IBM's Model M keyboard, produced in the mid-1990s.See also
* 15-M, Anti-austerity movement in Spain * MI5, the United Kingdom's counter-intelligence and security agency * Shorthand for Model 15 * '' Magic 2015'', a ''Magic: The Gathering'' expansion set {{Letter-Number Combination Disambiguation