Hudson Bay (Inuktitut: Kangiqsualuk ilua, French: baie d'Hudson), sometimes (usually historically) called Hudson's Bay, is a large body of saltwater in northeastern Canada. It drains a very large area, about 4,041,400 square kilometres (1,560,400 sq mi), that includes parts of Ontario, Quebec, Saskatchewan, Alberta, most of Manitoba, southeastern Nunavut, as well as parts of North Dakota, South Dakota, Minnesota, and Montana. The southern arm of Hudson Bay is called James Bay.

The Eastern Cree name for Hudson and James Bay is Wînipekw (Southern dialect) or Wînipâkw (Northern dialect), meaning muddy or brackish water. Lake Winnipeg is similarly named by the local Cree, as is the location for the City of Winnipeg.