J class or Class J may refer to:
Railways NBR J class, steam locomotives operated in the United Kingdom from 1909 NZR J class (1874), steam locomotives operating in New Zealand from 1874 until 1935 NZR J class (1939), steam locomotives operating in New Zealand from 1939 WAGR J class, steam locomotives operating in Western Australia from the 1890s WAGR J class (diesel), diesel locomotives operating in Western Australia from the 1960s Victorian Railways J class (1859), main line steam locomotives operating in Victoria, Australia from 1859 to 1912 Victorian Railways J class (1954), branch line steam locomotives operating in Victoria, Australia from 1954 to 1972 Norfolk and Western Railway class J (1879), steam locomotives operating in the United States from 1879 until 1900 Norfolk and Western Railway class J (1903), steam locomotives operating in the United States from 1903 until 1935 Norfolk and Western Railway class J (1941), steam locomotives operating in the United States from 1950 until 1959 South Australian Railways J class, steam locomotives operating in South Australia from 1875 until 1932 Tasmanian Government Railways J class, steam locomotive operating in Tasmania, Australia from 1901 until 1910 J-class Melbourne tram J-class Sydney tram
Watercraft , a racing yacht design constructed for the America's Cup competition between 1931 and 1937 , a class of British-built destroyers active from 1937 until 1949 , a class of British-built submarines operated by the Royal Navy and Royal Australian Navy between 1916 and 1930 , an Italian World War II boat
Other uses J-class blimp, 1920s airships J-segment, a European vehicle size class Class. J., the ISO 4 abbreviation for The Classical Journal. A code used by many airlines for business class
See also J type (disambiguation)