The H series was the third series of rapid transit rolling stock used in the subway system of Toronto, Ontario, Canada. They were built in six production sets, named H1 to H6, from 1965 to 1990 in Thunder Bay, Ontario, for the Toronto Transit Commission (TTC). The first five sets were manufactured by Hawker Siddeley Canada until 1979, when the company was purchased by the Urban Transportation Development Corporation (UTDC), which then took over production. They operated alongside their predecessor models, the M series, while the H6 trains replaced the last remaining G-series trains in 1990.