J18 may refer to: Vehicles Locomotives GSR Class J18, an Irish steam locomotive LNER Class J18, a British steam locomotive class Ships , a Hunt-class minesweeper of the Royal Navy , a Halland-class destroyer of the Swedish Navy , a Sandhayak-class survey ship of the Indian Navy Other uses Carnival Against Capital, an anti-globalisation protest held on June 18th 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 See also 18-j, 2004 film