J18

J18 may refer to:

Locomotives

 * GSR Class J18, an Irish steam locomotive
 * LNER Class J18, a British steam locomotive class

Ships

 * HMS Selkirk (J18), a Hunt-class minesweeper of the Royal Navy
 * HSWMS Halland, a Halland-class destroyer of the Swedish Navy
 * INS Sandhayak, a Sandhayak-class survey ship of the Indian Navy

Other uses

 * Carnival Against Capital, an anti-globalisation protest held on June 18, 1999
 * County Route J18 (California)
 * Elongated triangular cupola, a Johnson solid (J18)
 * J18 Elit, the highest level of under-18 ice hockey in Sweden
 * Pneumonia