Newfoundland.
See also: mainland (meaning 1a)
3 n. — Ethnicities, usually derogatory when used by outsiders
a native or resident of Newfoundland.
Type: 5. Frequency — This is the most common meaning today, used by both Newfoundlanders and mainlanders. In the North American context, the term is most frequent in Canada (see Chart 1). In South Africa (.za) and New Zealand (.nz), the term refers exclusively to the Newfoundland dog breed.
However, when used by mainlanders, Newfie acquires quite negative connotations (see, e.g. Newfie joke), which is why we recommend non-Newfoundlanders use the unclipped version: Newfoundlander (see also the 2007 quotation). See Chart 2, which shows that Prince Edward Islanders and Nova Scotians use the term almost three times as much as Newfoundlanders themselves.
See also: Newfie joke
Images:

Chart 1: Internet Domain Search, 8 Apr. 2016
Chart 2: Regional Domain Search, 7 Jul. 2016