The Royal Hudsons are a series of semi-streamlined 4-6-4 "Hudson" type steam locomotives formerly owned and operated by the Canadian Pacific Railway (CPR) and built by Montreal Locomotive Works (MLW). The engines were built in 1937. In 1939, King George VI allowed the CPR to use the term after Royal Hudson number 2850 transported the royal train across Canada with no need of replacement. These locomotives were in service between 1937 and 1960. Four of them have been preserved. No. 2839 was used to power excursions for the Southern Railway Steam Program between 1979 and 1980. No. 2860 was used for excursion service in British Columbia between 1974 and 1999, then again between 2006 and 2010.

Under the Whyte notation for the classification of locomotives, 4-6-4 represents the wheel arrangement of four leading wheels, six powered and coupled driving wheels and four trailing wheels. In France where the type was first used, it is known as the Baltic while it became known as the Hudson in most of North America.